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Sample records for deficient strontium cobaltate

  1. 40 CFR 721.10600 - Calcium cobalt lead strontium titanium tungsten oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Calcium cobalt lead strontium titanium... Specific Chemical Substances § 721.10600 Calcium cobalt lead strontium titanium tungsten oxide. (a... calcium cobalt lead strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0) is subject to...

  2. 40 CFR 721.10600 - Calcium cobalt lead strontium titanium tungsten oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Calcium cobalt lead strontium titanium... Specific Chemical Substances § 721.10600 Calcium cobalt lead strontium titanium tungsten oxide. (a... calcium cobalt lead strontium titanium tungsten oxide (PMN P-11-272; CAS No. 1262279-30-0) is subject to...

  3. Equilibrium sorption of cobalt, cesium, and strontium on Bandelier Tuff: analysis of alternative mathematical modeling

    SciTech Connect

    Polzer, W.L.; Fuentes, H.R.; Essington, E.H.; Roensch, F.R.

    1985-01-01

    Sorption isotherms are derived from batch equilibrium data for cobalt, cesium and strontium on Bandelier Tuff. Experiments were conducted at an average temperature of 23/sup 0/C and equilibrium was defined at 48 hours. The solute concentrations ranged from 0 to 500 mg/L. The radioactive isotopes /sup 60/Co, /sup 137/Cs, and /sup 85/Sr were used to trace the sorption of the stable solutes. The Linear, Langmuir, Freundlich and a Modified Freundlich isotherm equations are evaluated. The Modified Freundlich isotherm equation is validated as a preferred general mathematical tool for representing the sorption of the three solutes. The empirical constants derived from the Modified Freundlich isotherm equation indicate that under dynamic flow conditions strontium will move most rapidly and cobalt least rapidly. On the other hand, chemical dispersion will be greatest for cesium and least for strontium. Hill Plots of the sorption data suggest that in the region of low saturation sorption of all three solutes is impeded by interactions among sorption sites; cobalt exhibits the greatest effect of interactions and strontium shows only a minimal effect. In the saturation region of 50% or more, sorption of cobalt is enhanced slightly by interactions among sorption sites whereas sorption of cesium and strontium appears to be independent of site interactions. 9 references, 4 figures, 2 tables.

  4. Water hyacinths and alligator weeds for removal of silver, cobalt, and strontium from polluted waters

    NASA Technical Reports Server (NTRS)

    Wolverton, B. C.; Mcdonald, R. C.

    1975-01-01

    Water hyacinths and alligator weeds demonstrated the ability to rapidly remove heavy metals from an aqueous system by root absorption and concentration. Water hyacinths demonstrated the ability to remove 0.439 mg of silver, 0.568 mg of cobalt, and 0.544 mg of strontium in an ionized form per gram of dry plant material in a 24-hour period. Alligator weeds removed a maximum of 0.439 mg of silver, 0.130 mg of cobalt, and 0.161 mg of strontium per gram of dry plant material per day.

  5. Thermal conductivity reduction in oxygen-deficient strontium titanates

    NASA Astrophysics Data System (ADS)

    Yu, Choongho; Scullin, Matthew L.; Huijben, Mark; Ramesh, Ramamoorthy; Majumdar, Arun

    2008-05-01

    We report significant thermal conductivity reduction in oxygen-deficient lanthanum-doped strontium titanate (Sr1-xLaxTiO3-δ) films as compared to unreduced strontium titanates. Our experimental results suggest that the oxygen vacancies could have played an important role in the reduction. This could be due to the nature of randomly distributed and clustered vacancies, which would be very effective to scatter phonons. Our results could provide a pathway for tailoring the thermal conductivity of complex oxides, which is very beneficial to various applications including thermoelectrics.

  6. Relaxation behavior of oxygen deficient strontium manganite

    SciTech Connect

    Pandey, Namita Thakur, Awalendra Kumar

    2014-04-24

    Conduction behavior of nanocrystalline oxygen deficient ceramic-SrMnO{sub 3–δ}(δ∼0.14) has been studied. The structural analysis of nano-SrMnO{sub 2.86} follows hexagonal unit cell structure with P6{sub 3}/mmc (194) space group belonging to 6/mmm point group with 4H – layered type hexagonal-cubic layers. The system have lattice parameters; a = 5.437(92) Å, c = 9.072(92) Å, c/a∼1.66 (85) with α =90° γ= 120° and cell volume, V= 232.35(18). The relaxation times estimated from complex impedance and modulus relaxation spectrum, show the thermally activated system with corresponding activation energies as 0.66 eV and 0.51 eV The stretching factor ‘β’ from the scaled modulus spectrum shows the poly-dispersive non-Debye nature of the system. The hopping number ‘n’ shows the influence of ionic charge carriers which controls the conduction mechanism of nano-SrMnO{sub 2.86}.

  7. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    1995-01-01

    Part of the 1994 Industrial Minerals Review. The production, consumption, and applications of strontium are reviewed. Consumption for the year is estimated to have been about 35 kt for strontium contained in celestite, strontium carbonate, and strontium nitrate. Exports of strontium totaled only about 1.1 kt for the year. U.S. strontium imports and consumption increased about 30 percent in 1994 due to increased domestic production of color television picture tube glass. The average customs value of celestite coming into the U.S. was about $75/t, strontium carbonate was valued at $661/t, and strontium nitrate was valued at about $1,069/t.

  8. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    1996-01-01

    Part of the Annual Commodities Review 1995. In 1995, U.S. strontium imports and consumption increased nearly 30 percent due to increased domestic production of color television picture tube glass. However, strontium compound exports fell during 1995. Strontium is also used in the production of permanent ceramic ferrite magnets. Strontium nitrate, strontium chromate, and strontium chloride are also commonly used materials. Although the development of an affordable flatscreen display could eliminate the need for strontium in television production, this technology is not expected to be perfected in the immediate future.

  9. Cobalt dicarbollide containing polymer resins for cesium and strontium uptake

    SciTech Connect

    Steckle, W.P. Jr.; Duke, J.R. Jr.; Jorgensen, B.S.

    1994-04-01

    Cobalt(III) dicarbollide [(C{sub 2}B{sub 9}H{sub 11}){sub 2}Co]{sup {minus}} (CB{sub 2}) is being investigated for Cs and Sr extraction from nuclear waste. Because organic solvents should be avoided, bonding of CB{sub 2} to resins were investigated. CB{sub 2} was successfully covalently bonded to polystyrene and polybenzimidazole resins. Tetrahydrofuran was the most efficient solvent for grafting. Analysis is being performed, and separation coefficients are also being determined. 3 figs, 8 refs.

  10. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    NASA Astrophysics Data System (ADS)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

  11. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    2000-01-01

    Mexico is the leading producer of celestite, the most common strontium ore. Chemical Products is the only major US maker of strontium compounds. It produces all of its strontium carbonate from imported Mexican celestite. Mexico is also a large producer of strontium carbonate, as are China, Germany, Japan and the Republic of Korea. There has been no celestite production in the United States since 1959.

  12. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    2006-01-01

    China, Mexico, Spain and Turkey are the world's leading producers of celestite (strontium sulphate). These countries accounted for 98% of the total world production in 2005. For the same period, US apparent consumption of strontium decreased to 12.3 kt. Imports were 21.2 kt, of which 84% came from Mexico. Imports of celestite and strontium carbonate decreased 71% and 24% respectively.

  13. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    1994-01-01

    Production figures are not published for stronium carbonate because there is only one company producing strontium carbonate domestically. Strontium carbonate is produced in the U.S. from imported celestite. Consumption can be estimated from trade data published by the U.S. Bureau of the Census. Consumption is estimated at approximately 24.5 kt of strontium. The largest end-use of strontium carbonate is in the production of faceplate glass for color television picturetubes. Other applications and markets for strontium are discussed.

  14. Chemical and electronic characterization of cobalt in a lanthanum perovskite. Effects of strontium substitution

    SciTech Connect

    Hueso, Jose L.; Holgado, Juan P.; Pereniguez, Rosa; Mun, Simon; Salmeron, Miquel; Caballero, Alfonso

    2010-01-15

    Two different cobaltites, LaCoO{sub 3} and La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}}, have been prepared and characterized by means of high energy Co K-edge and low energy O K-edge X-ray absorption spectroscopy (XAS). Even though half of the La(III) is substituted by Sr(II), little or no changes can be detected in the formal oxidation state of cobalt atoms. The presence of strontium cations induces two main effects in the chemical and electronic state of the perovskite. The charge balance with Sr(II) species is reached by the formation of oxygen vacancies throughout the network, which explains the well-known increase in the reactivity of this substituted perovskite. O K-edge XAS experiments show that the Sr(II) species induce the transitions of d electrons of cobalt cations from low to high spin configuration. We propose that this change in spin multiplicity is induced by two cooperative effects: the oxygen vacancies, creating five coordinated cobalt atoms, and the bigger size of Sr(II) cations, aligning the Co-O-Co atoms, and favoring the overlapping of pi-symmetry cobalt and oxygen orbitals, reducing the splitting energy of e{sub g} and t{sub 2g} levels. - Graphical abstract: Change in spin multiplicity induced by the bigger size of Sr(II) cations, aligning the Co-O-Co atoms, and favoring the overlapping of pi-symmetry cobalt and oxygen orbitals.

  15. Chemical and electronic characterization of cobalt in Lanthanumperovskites. Effects of Strontium substitution

    SciTech Connect

    Hueso, Jose L.; Holgado, Juan P.; Pereniguez, Rosa; Mun, Simon; Salmeron, Miquel; Caballero, Alfonso

    2009-02-06

    Two different cobaltites, LaCoO{sub 3} and La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}}, have been prepared and characterized by means of high energy Co K-edge and low energy O K-edge X-ray absorption spectroscopy (XAS). The partial substitution of La(III) by Sr(II) species induces important changes in the reactivity and electronic state of the perovskite, while little or no changes can be detected in the formal oxidation state of cobalt atoms. The presence of strontium cations induces two main effects in the chemical and electronic behavior of the perovskite. The charge balance with Sr(II) species is reached by the formation of oxygen vacancies throughout the network, which increases the reactivity of the perovskite, now more reducible than the original LaCoO{sub 3} perovskite. O K-edge XAS experiments indicate that the Sr(II) species cause d electrons of cobalt cations to change from low to high spin configuration. Our data allow us to propose that this change in spin multiplicity is induced by the bigger size of Sr(II) cations, which aligns the Co-O-Co atoms, and favors the overlapping of {pi}-symmetry cobalt and oxygen orbitals, reducing the splitting energy of e{sub g} and t{sub 2g} levels.

  16. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    2013-01-01

    In 2012, U.S. apparent consumption of strontium (contained in celestite and manufactured strontium compounds) decreased to 16.7 kt (18,400 st) from 17.3 kt (19,100 st) in 2011. Gross weight of imports was 34.3 kt (37,800 st), 86 percent of which originated in Mexico.

  17. Strontium

    USGS Publications Warehouse

    Angulo, M.A.

    2011-01-01

    In 2010, U.S. apparent consumption of strontium (contained in celestite and manufactured strontium compounds) decreased by 11 percent to 10.4 kt (11,460 st) from 11.8 kt (13,000 st) in 2009. Gross weight of imports totaled 20.9 kt (23,000 st), of which 65 percent originated from Mexico.

  18. Strontium

    USGS Publications Warehouse

    ,

    2012-01-01

    In 2011, U.S. apparent consumption of strontium (contained in celestite and manufactured strontium compounds) increased markedly to 18.4 kt (20,300 st) from 10.4 kt (11,500 st) in 2010. Gross weight of imports was 34.4 kt (38,000 st), of which 76 percent originated from Mexico.

  19. Persistent optically induced magnetism in oxygen-deficient strontium titanate.

    PubMed

    Rice, W D; Ambwani, P; Bombeck, M; Thompson, J D; Haugstad, G; Leighton, C; Crooker, S A

    2014-05-01

    Strontium titanate (SrTiO3) is a foundational material in the emerging field of complex oxide electronics. Although its bulk electronic and optical properties are rich and have been studied for decades, SrTiO3 has recently become a renewed focus of materials research catalysed in part by the discovery of superconductivity and magnetism at interfaces between SrTiO3 and other non-magnetic oxides. Here we illustrate a new aspect to the phenomenology of magnetism in SrTiO3 by reporting the observation of an optically induced and persistent magnetization in slightly oxygen-deficient bulk SrTiO3-δ crystals using magnetic circular dichroism (MCD) spectroscopy and SQUID magnetometry. This zero-field magnetization appears below ~18 K, persists for hours below 10 K, and is tunable by means of the polarization and wavelength of sub-bandgap (400-500 nm) light. These effects occur only in crystals containing oxygen vacancies, revealing a detailed interplay between magnetism, lattice defects, and light in an archetypal complex oxide material.

  20. Strontium

    USGS Publications Warehouse

    Angulo, M.A.

    2010-01-01

    In 2009, U.S. apparent consumption of strontium (contained in celestite and manufactured strontium compounds) increased to 16 kt (17,600 st) from 10.6 kt (11,700 st) in 2008, an increase of 52 percent. This increase was attributed primarily to an increase in imported celestite. Gross weight of imports totaled 25.3 kt (27,900 st), of which 91 percent came from Mexico. Imports in 2009 were 18 percent more than in 2008. Exports of strontium compounds in 2009 decreased 15 percent to 9.3 kt (10,250 st) from 10.9 kt (12,000 st) in 2008. In 2009, the U.S. Customs value of imported strontium carbonate was 65 cents/kg (29 cents/lb); for strontium nitrate, the unit value was $ 1/kg (45 cents/lb). The unit value of imported celestite, all of which was from Mexico, was about $47/t ($43/st).

  1. Microstructural, dielectric and magnetic properties of multiferroic composite system barium strontium titanate – nickel cobalt ferrite

    SciTech Connect

    Pahuja, Poonam Tandon, R. P.

    2015-05-15

    Multiferroic composites (1-x) Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} + (x) Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} (where x = 0.1, 0.2, 0.3, 0.4) has been prepared by solid state reaction method. X-ray diffraction analysis of the composite samples confirmed the presence of both barium strontium titanate (BST) and nickel cobalt ferrite (NCF) phases. FESEM images indicated the well dispersion of NCF grains among BST grains. Dielectric constant and loss of the composite samples decreases with increase in frequency following Maxwell-Wagner relaxation mechanism. Composite sample with highest ferrite content possesses highest values of remanent and saturation magnetization.

  2. Sodium cobalt hexacyanoferrate encapsulated in alginate vesicle with CNT for both cesium and strontium removal.

    PubMed

    Vipin, Adavan Kiliyankil; Ling, Sun; Fugetsu, Bunshi

    2014-10-13

    Sodium cobalt hexacyanoferrate (CoFC)-encapsulating alginate beads reinforced with highly dispersed multiwalled carbon nanotubes were prepared for the aqueous removal of cesium and strontium ions. Carbon nanotubes enhanced the effective surface area, encapsulation ability and adsorption capacity of beads. Equilibrium and kinetic studies were conducted with different mathematical models. The goodness of mathematical fitting of experimental data on the adsorption isotherm model was in the order Langmuir higher than Freundlich. The maximum Cs(+)/Sr(2+) adsorption capacity of beads modified with carbon nanotubes were 133/72 mg/g and that of beads without carbon nanotubes were 121/70 mg/g. Similarly in kinetic models pseudo-second-order gave better fitting than pseudo-first-order. The performance of beads was consistent in a wide range of pH as well as in high ionic competitions. The fixed bed adsorption column analysis indicated that beads can be used for large scale treatment of cesium and strontium contaminated water.

  3. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    1993-01-01

    Part of a special section reviewing the market performance of industrial minerals in 1992. Imports of celestite (strontium ore) reached nearly 45 kt, which represents an increase of 35 percent over 1991. Mexico supplied almost all of the celestite. Nearly 70 percent of the strontium consumed in the U.S. is used in television picture tube faceplate glass to block X-ray emissions.

  4. Strontium

    Integrated Risk Information System (IRIS)

    Strontium ; CASRN 7440 - 24 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  5. Strontium

    USGS Publications Warehouse

    Ober, J.A.

    2003-01-01

    Mexico and Spain are the leading producers of celestite, the most common strontium ore. Those countries produced nearly 80 percent of the estimated 360 kt (397,000 st) of celestite produced worldwide during 2002. China and Turkey are other significant celestite producers.

  6. Boron-Doped Strontium-Stabilized Bismuth Cobalt Oxide Thermoelectric Nanocrystalline Ceramic Powders Synthesized via Electrospinning

    NASA Astrophysics Data System (ADS)

    Koçyiğit, Serhat; Aytimur, Arda; Çınar, Emre; Uslu, İbrahim; Akdemir, Ahmet

    2014-01-01

    Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by using a polymeric precursor technique. The powders were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), and physical properties measurement system (PPMS) techniques. The XRD results showed that these patterns have a two-phase mixture. The phases are face-centered cubic (fcc) and body-centered cubic (bcc). Values of the crystallite size, dislocation density, and microstrain were calculated by using the Scherrer equation. The lattice parameters were calculated for fcc and bcc phases. The SEM results showed that needle-like grains are formed in boron-undoped composite materials, but the needle-like grains changed to the plate-like grains with the addition of boron. The distribution of the nanofiber diameters was calculated and the average diameter of the boron-doped sample is smaller than the boron-undoped one. PPMS values showed that the electrical resistivity values decreased, but the thermal conductivity values, the Seebeck coefficients, and figure of merit ( ZT) increased with increasing temperature for the two samples.

  7. Crystal-field interaction and oxygen stoichiometry effects in strontium-doped rare-earth cobaltates

    NASA Astrophysics Data System (ADS)

    Furrer, A.; Podlesnyak, A.; Frontzek, M.; Sashin, I.; Embs, J. P.; Mitberg, E.; Pomjakushina, E.

    2014-08-01

    Inelastic neutron scattering was employed to study the crystal-field interaction in the strontium-doped rare-earth compounds RxSr1-xCoO3-z (R=Pr, Nd, Ho, and Er). Particular emphasis is laid on the effect of oxygen deficiencies that naturally occur in the synthesis of these compounds. The observed energy spectra are found to be the result of a superposition of crystal fields with different nearest-neighbor oxygen coordination at the R sites. The experimental data are interpreted in terms of crystal-field parameters, which behave in a consistent manner through the rare-earth series, thereby allowing a reliable extrapolation for rare-earth ions not considered in the present work.

  8. Preparation and use of tetra-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents

    DOEpatents

    Miller, Rebecca L.; Pinkerton, Anthony B.; Abney, Kent D.; Kinkead, Scott A.

    1997-01-01

    Preparation and use of tetra-C-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents. Tetra-C-alkyl derivatives of cobalt dicarbollide, Co(C.sub.2 R.sub.2 B.sub.9 H.sub.9).sub.2.sup.- (CoB.sub.2 R.sub.4.sup.- ; R=CH.sub.3 and C.sub.6 H.sub.13) are demonstrated to be significant cesium and strontium extractants from acidic and alkaline solutions into non-toxic organic solvent systems. Extractions using mesitylene and diethylbenzene are compared to those with nitrobenzene as the organic phase. CoB.sub.2 -hexyl.sub.4.sup.- in diethylbenzene shows improved selectivity (10.sup.4) for Cs over Na in acidic solution. In dilute alkaline solution, CoB.sub.2 -hexyl.sub.4.sup.- extracts Cs less efficiently, but more effectively removes Sr from higher base concentrations. A general synthesis of tetra-C-alkyl cobalt dicarbollides is described.

  9. Preparation and use of tetra-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents

    DOEpatents

    Miller, R.L.; Pinkerton, A.B.; Abney, K.D.; Kinkead, S.A.

    1997-02-11

    Preparation and use of tetra-C-alkyl cobalt dicarbollide for extraction of cesium and strontium into hydrocarbon solvents. Tetra-C-alkyl derivatives of cobalt dicarbollide, Co(C{sub 2}R{sub 2}B{sub 9}H{sub 9}){sub 2}{sup {minus}}(CoB{sub 2}R{sub 4}{sup {minus}}; R=CH{sub 3} and C{sub 6}H{sub 13}) are demonstrated to be significant cesium and strontium extractants from acidic and alkaline solutions into non-toxic organic solvent systems. Extractions using mesitylene and diethylbenzene are compared to those with nitrobenzene as the organic phase. CoB{sub 2}-hexyl{sub 4}{sup {minus}} in diethylbenzene shows improved selectivity (10{sup 4}) for Cs over Na in acidic solution. In dilute alkaline solution, CoB{sub 2}-hexyl{sub 4}{sup {minus}} extracts Cs less efficiently, but more effectively removes Sr from higher base concentrations. A general synthesis of tetra-C-alkyl cobalt dicarbollides is described. 6 figs.

  10. STRONTIUM PRECIPITATION

    DOEpatents

    McKenzie, T.R.

    1960-09-13

    A process is given for improving the precipitation of strontium from an aqueous phosphoric-acid-containing solution with nickel or cobalt ferrocyanide by simultaneously precipitating strontium or calcium phosphate. This is accomplished by adding to the ferrocyanide-containing solution calcium or strontium nitrate in a quantity to yield a concentration of from 0.004 to 0.03 and adjusting the pH of the solution to a value of above 8.

  11. Decontamination of cesium, strontium, and cobalt from aqueous solutions by bentonite

    SciTech Connect

    Khan, M.A.; Khan, S.A.

    1996-12-31

    Sorption studies of cesium, strontium, and cobalt (Cs, Sr, and Co) on bentonite under various experimental conditions, such as contact time, pH, sorbent and sorbate concentration, and temperature, have been performed. The sorption data for all these metals have been interpreted in terms of Freundlich, Langmuir, and Dubinin-Radushkevich equations. Thermodynamics parameters, such as heat of sorption {Delta}H{degrees}, free energy change {Delta}G{degrees}, and entropy change {Delta}S{degrees}, for the sorption of these metals on bentonite have been calculated. The value of {Delta}H{degrees} shows that the sorption of Cs was exothermic, while the sorption of Sr and Co on bentonite were endothermic in nature. The value of {Delta}G{degrees} for their sorption was negative, showing the spontaneity of the process. The maximum loading capacity of Cs, Sr, and Co were 75.5, 22, and 27.5 meq, respectively, for 100 g of bentonite. The mean free energy E of Cs, Sr, and Co sorption on bentonite was 14.5, 9, and 7.7 kJ/mol, respectively. The value of E indicates that ion exchange may be the predominant mode of sorption for these radionuclides. The desorption studies with 0.01 M CaCl{sub 2} and groundwater at low-metal loading on bentonite showed that about 95% of Cs, 85-90% of Sr, and 97% of Co were irreversibly sorbed. Bentonite could be effectively used for the decontamination of wastewater effluent containing low concentrations of radioactive nuclides of Cs, Sr, and Co. 16 refs., 7 figs., 3 tabs.

  12. Cobalt deficiency effects on trace elements, hormones and enzymes involved in energy metabolism of cattle.

    PubMed

    Stangl, G I; Schwarz, F J; Kirchgessner, M

    1999-03-01

    This study was conducted to investigate the physiological consequences of long-term moderate cobalt deficiency in beef cattle, which have not hitherto been studied in detail. Cobalt deficiency was induced in cattle by feeding two groups of animals either a basal corn silage-based diet that was moderately low in cobalt (83 micrograms Co/kg), or the same diet supplemented with cobalt to a total of 200 micrograms per kg, for 43 weeks. Cobalt deficiency was induced, as judged by inappetance, diminished growth gain and a markedly reduced vitamin B12 status in serum and liver. The long-term cobalt deprivation which was primarily a combination of reduced feed intake and a tissue vitamin B12 deficiency did not show evidence of a significant dysfunction of energy metabolism. The activities of glucose-6-phosphate dehydrogenase and cytochrome oxidase in liver remained unaffected by cobalt deficiency, nor was there a significant change in serum glucose level of cattle on the cobalt-deprived diet. However, analysis of thyroid hormone status indicated a slight reduction of type I thyroxine monodeiodinase activity in liver accompanied by a significant reduction of the triiodothyronine level in serum. The diminished liver vitamin B12 level resulted in significantly reduced folate level in this tissue, reduced concentrations of heme-depending blood parameters. Moreover cobalt deficiency or rather vitamin B12 deficiency was accompanied by a dramatic accumulation of the trace elements iron and nickel in liver. These results indicate that long-term moderate cobalt deficiency may induce a number of physiological changes in cattle, but a follow-up study, which excluded different feed levels by including a pair-fed control group, will be necessary to actually obtain the single effect of cobalt deficiency in cattle.

  13. Investigation of lanthanum-strontium-cobalt ferrites using laser ablation inductively coupled plasma-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Óvári, Mihály; Tarsoly, Gergely; Németh, Zoltán; Mihucz, Victor G.; Záray, Gyula

    2017-01-01

    In the present study, suitability of laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for characterization of the purity and homogeneity of lanthanum-strontium-cobalt ferrite (LSCF) ceramic microsamples with general formula La1 - xSrxFe0.025Co0.975O3 (0.00 ≤ x ≤ 0.50) was studied through determination of their Sr:La ratios as well as Sr content either in depth or line profiling mode. The Sr content of the LSCF samples expressed as weight percent ranged between 5.8% and 9.7% in the case of wet chemical ICP-MS analysis, while theoretical values varied from 5.5% to 9.4%. In the case of LA-ICP-MS, relative standard deviation of the La-normalized Sr intensities was sufficient to characterize the homogeneity of the studied samples. Major and trace element (Mn, Ni, Cu, Mg, Al, Ba) concentrations could be detected at medium resolution of the applied sector field ICP-MS instrument after microwave-assisted acid digestion. For depth and line profiling, a successful approach consisted of the normalization of intensities of Sr, Fe and Co with the corresponding La counts. For the determination of the elemental ratios of La and Sr, the methods involving LA were in good agreement with theoretical values by standardization to an in-house standard corresponding to the LSCF sample having the highest x value (i.e., 0.50) checked by wet chemical ICP-MS measurements. Thus, assessment of fine scale doping of synthesized perovskite type of microsamples could be achieved by the proposed LA-ICP-MS based on a novel calibration approach applying an in-house perovskite standard. Therefore, LA-ICP-MS can be recommended for quality control of perovskite-based products. In memoriam Attila Vértes (1934-2011), full professor of the Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary.

  14. Strontium- and cobalt-substituted bioactive glasses seeded with human umbilical cord perivascular cells to promote bone regeneration via enhanced osteogenic and angiogenic activities.

    PubMed

    Kargozar, Saeid; Lotfibakhshaiesh, Nasrin; Ai, Jafar; Mozafari, Masoud; Brouki Milan, Peiman; Hamzehlou, Sepideh; Barati, Mahmood; Baino, Francesco; Hill, Robert G; Joghataei, Mohammad Taghi

    2017-08-01

    Designing and developing new biomaterials to accelerate bone healing are currently under progress. In this study, we attempted to promote osteogenesis using strontium- and cobalt-substituted bioactive glasses (BGs) seeded with human umbilical cord perivascular cells (HUCPVCs) in a critical size defect in the distal femur of rabbit animal model. The BG particles were successfully synthesized in the form of granules using the melt-derived route. After being isolated, HUCPVCs were expanded and then characterized to use during in vitro and in vivo procedures. The in vitro effects of the synthesized glasses on the isolated HUCPVCs as well as on cell lines SaOS-2 (selected for screening the osteogenetic potential) and HUVEC (selected for screening the angiogenic potential) were assessed by analyzing cytotoxicity, cell attachment, bone-like nodule formation, and real time PCR. The results of in vitro tests indicated cytocompatibility of the synthesized BG particles. For in vivo study, the HUCPVCs-seeded BGs were implanted into the animal's body. Radiographic imaging, histology and immunohistology staining were performed on the harvested specimens at 4 and 12weeks post-surgery. The in vivo evaluation of the samples showed that all the cell/glass constructs accelerated bone healing process in comparison with blank controls. The best in vitro and in vivo results were associated to the BGs containing both strontium and cobalt ions. This group of bioactive glasses is able to promote both osteogenesis and angiogenesis and can therefore be highly suitable for the development of advanced functional bone substitutes. Bone regeneration is considered as an unmet clinical need. The most recent researches focused on incorporation of strontium (Sr(2+)) and cobalt (Co(2+)) ions into bioactive glasses structure. Strontium is an alkaline earth metal which is currently used in the treatment of osteoporosis. Also, cobalt is considered as another promising element in the bone regeneration

  15. Comparison of effects of overload on parameters and performance of samarium-cobalt and strontium-ferrite radially oriented permanent magnet brushless DC motors

    SciTech Connect

    Demerdash, N.A.; Nehl, T.W.; Nyamusa, T.A.

    1985-08-01

    Effects of high momentary overloads on the samarium-cobalt and strontium-ferrite permanent magnets and the magnetic field in electronically commutated brushless dc machines, as well as their impact on the associated machine parameters were studied. The effect of overload on the machine parameters, and subsequently on the machine system performance was also investigated. This was accomplished through the combined use of finite element analysis of the magnetic field in such machines, perturbation of the magnetic energies to determine machine inductances, and dynamic simulation of the performance of brushless dc machines, when energized from voltage source inverters. These effects were investigated through application of the above methods to two equivalent 15 hp brushless dc motors, one of which was built with samarium-cobalt magnets, while the other was built with strontium- ferrite magnets. For momentary overloads as high as 4.5 p.u. magnet flux reductions of 29% and 42% of the no load flux were obtained in the samarium-cobalt and strontiumferrite machines, respectively. Corresponding reductions in the line to line armature inductances of 52% and 46% of the no load values were reported for the samarium-cobalt and strontium-ferrite cases, respectively. The overload affected the profiles and magnitudes of armature induced back emfs. Subsequently, the effects of overload on machine parameters were found to have significant impact on the performance of the machine systems, where findings indicate that the samarium-cobalt unit is more suited for higher overload duties than the strontium-ferrite machine.

  16. An oxygen-deficiency modulated multiferroic: Cobalt-substituted perovskite

    NASA Astrophysics Data System (ADS)

    Florez, Juan Manuel

    In this work, we use density functional theory to model recently demonstrated room temperature ferromagnetism and ferroelectricity in polycrystalline and single crystal Cobalt-substituted SrTiO3 thin films (SrTi0.70Co0.30O3-d), deposited at different oxygen pressures to change their oxygen vacancy concentration. The modeling indicates an origin for both magnetism and electric polarization in the interactions between oxygen vacancies and the B-site cations. The magnetization saturation increases with the oxygen deficiency as a result of valence spin states changes, which depend on whether the oxygen octahedral of the respective local B-site cations are complete or not. On the other hand, a finite electric polarization appears as a result of a non-centrosymmetric distribution of different resulting local charges and such a polarization increases when the oxygen vacancies increase. Increasing of both order parameters, magnetic and ferroelectric, are analyzed respect to all possible Co-sites and O-vacancies distributions, showing that these results suggest a class of multiferroic materials with properties controlled by their oxygen stoichiometry. Agreement and discrepancies between experiments and modeling are discussed. 1J M Florez and P Vargas thank Fondecyt 1130950 and 11130128, all authors thank the MISTI MIT-Chile, and CAR thanks the (S3TEC) and DoE under DE-SC0001299.

  17. Preparation and electrical properties of yttrium-doped strontium titanate with B-site deficiency

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Zhao, Hailei; Li, Xue; Cheng, Yunfei; Zhou, Xiong; Cui, Fenge

    Yttrium-doped strontium titanate with B-site deficiency (Y 0.08Sr 0.92Ti 1- xO 3- δ) is synthesized via conventional solid-state reaction. The effect of B-site deficiency on the lattice parameter, sinterability, microstructure and electrical properties of Y 0.08Sr 0.92TiO 3- δ is investigated. The charge compensation mechanism for B-site deficiency is proposed. The limit of B-site deficiency in Y 0.08Sr 0.92Ti 1- xO 3- δ is below 5 mol % in Ar with 5% H 2 at 1500 °C. The sinterability of Y 0.08Sr 0.92Ti 1- xO 3- δ decreases slightly with increasing deficiency level (x). Compared with Y 0.08Sr 0.92TiO 3- δ, the electrical conductivity of Y 0.08Sr 0.92Ti 1- xO 3- δ samples decreases while the ionic conductivity increases with increasing B-site deficient amount. It is assumed that the deficiency of Ti in Y 0.08Sr 0.92Ti 1- xO 3- δ is charge compensated by the increase of oxygen vacancy concentration and the decrease of Ti 3+ concentration. Y 0.08Sr 0.92Ti 1- xO 3- δ shows a relatively stable electrical conductivity at different oxygen partial pressures and displays an excellent chemical compatibility with YSZ electrolyte below 1200 °C.

  18. Evaluation of Cuprimine® and Syprine® for Decorporation of Radioisotopes of Cesium, Cobalt, Iridium, and Strontium

    SciTech Connect

    Levitskaia, Tatiana G.; Creim, Jeffrey A.; Curry, Terry L.; Luders, Teresa; Peterson, James M.; Thrall, Karla D.; Levinson, Barry

    2011-08-01

    Cuprimine and Syprine are therapeutics approved by FDA to treat copper overload in Wilson Disease (a genetic defect in copper transport) by chelation and accelerated excretion of internally deposited copper. These oral therapeutics are based on respective active ingredients D-penicillamine (DPA) and N,N'-bis (2-aminoethyl)-1,2-ethanediamine dihydrochloride (Trien). Cuprimine is considered the primary treatment, although physicians increasingly are turning to Syprine as first-line therapy. Both drugs exhibit oral systemic activity and low toxicity; their biological effects and safety are established. The literature reports that these agents exhibit high affinity for a range of transition and f-metals and metalloids in vitro. Our previous in vivo studies using a rodent animal model established the decorporation potential of Cuprimine and Syprine for cobalt-60 and polonium-210 (Levitskaia et al 2010a). Currently we are expanding these studies to evaluate in vivo decorporation efficacy of these drugs for several additional radionuclides. In this paper, we discuss results of this investigation using gamma-emitting radionuclides including cesium-137 (137Cs), cobalt-60 (60Co), iridium-192 (192Ir), and strontium-85 (85Sr). Short-term 48 hr pilot studies were undertaken to evaluate DPA and Trien for their in vivo decorporation potency using male Wistar-Han rats. In these studies, radionuclide solution was administered to animals by IV injection, followed by a single IV dose of either DPA or Trien. Control animals received the radionuclide alone. Results show highly effective decorporation of 60Co by DPA. DPA and Trien were modestly effective in decorporation 137Cs and 85Sr, respectively. Based on these promising findings, further studies to evaluate the dose-response pharmacokinetic profiles for decorporation are warranted.

  19. Cobalt.

    PubMed

    Fowler, Joseph F

    2016-01-01

    Cobalt has been a recognized allergen capable of causing contact dermatitis for decades. Why, therefore, has it been named 2016 "Allergen of the Year"? Simply put, new information has come to light in the last few years regarding potential sources of exposure to this metallic substance. In addition to reviewing some background on our previous understanding of cobalt exposures, this article will highlight the recently recognized need to consider leather as a major site of cobalt and the visual cues suggesting the presence of cobalt in jewelry. In addition, a chemical spot test for cobalt now allows us to better identify its presence in suspect materials.

  20. Cobalt

    SciTech Connect

    1993-02-01

    Cobalt is typical a by- or co-product with copper or nickel. The average crustal abundance of cobalt is 23 pans per million. Cobalt-containing minerals include cobaltite, skutterudite, and linnaeite. Due to the diversity of cobalt deposits, several techniques are used to extract the ore. The copper/cobalt-bearing ores of Zaire are extracted by open pit and underground methods. In Zambia, similar deposits are mined using modified sublevel, and cut-and-fill underground stoping methods. The sulfide and oxide ore concentrates mined in Zaire are roasted and leached in sulfuric acid. Copper is subsequently recovered by electrolysis, and cobalt is precipitated in the form of a hydrate. Finally, the hydrate is dissolved in acid and cobalt is recovered by electrolysis.

  1. Cobalt

    SciTech Connect

    Fox, G.J.

    1994-12-01

    Traditionally, cobalt has been well-known for its chemical uses, including pigments used in ceramic glazes that create the popular cobalt blue color derived from cobalt aluminate. Because of its diverse physical properties, the element is linked to many other applications, including superalloys, permanent magnets, and chemical catalysts. Cobalt 60, a radioisotope of cobalt, continues to be a contributor to the success of high-technology advancements, including innovations in medical treatments. Typically a by-product of copper and nickel production, significant cobalt reserves are found in only a few countries. The African countries of Zaire and Zambia, as well as Canada, are leading cobalt producers. Although the USA is the world's largest consumer, accounting for about one-third of total consumption, it has no domestic production and relies solely upon foreign imports to satisfy demand. The world market has been plagued with the effects of economic and political factors throughout the years, and consequently, price instability has been common. Presently, supply and demand are moving toward a closer balance, and lower market prices are expected within the next year.

  2. Micronutrients and kelp cultures: Evidence for cobalt and manganese deficiency in Southern California deep seawater

    USGS Publications Warehouse

    Kuwabara, J.S.

    1982-01-01

    It has been suggested that naturally occurring copper and zinc concentrations in deep seawater are toxic to marine organisms when the free ion forms are overabundant. The effects of micronutrients on the growth of gametophytes of the ecologically and commercially significant giant kelp (Macrocystis pyrifera) were studied in defined media. The results indicate that toxic copper and zinc ion concentrations as well as cobalt and manganese deficiencies may be among the factors controlling the growth of marine organisms in nature. Copyright ?? 1982 AAAS.

  3. Micronutrients and kelp cultures: evidence for cobalt and manganese deficiency in southern California deep seawater

    SciTech Connect

    Kuwabara, J.S.

    1982-06-11

    It has been suggested that naturally occurring copper and zinc concentrations in deep seawater are toxic to marine organisms when the free ion forms are overabundant. The effects of micronutrients in the growth of gametophytes of the ecologically and commercially significant giant kelp (Macrocystis pyrifera) were studied in defined media. The results indicate that toxic copper and zinc ion concentrations as well as cobalt and manganese deficiencies may be among the factors controlling the growth of marine organisms in nature.

  4. Fabrication of lanthanum strontium cobalt ferrite (LSCF) cathodes for high performance solid oxide fuel cells using a low price commercial inkjet printer

    NASA Astrophysics Data System (ADS)

    Han, Gwon Deok; Neoh, Ke Chean; Bae, Kiho; Choi, Hyung Jong; Park, Suk Won; Son, Ji-Won; Shim, Joon Hyung

    2016-02-01

    In this study, we investigate a method to fabricate high quality lanthanum strontium cobalt ferrite (LSCF) cathodes for solid oxide fuel cells (SOFCs) using a commercial low price inkjet printer. The ink source is synthesized by dissolving the LSCF nanopowder in a water-based solvent with a proper amount of surfactants. Microstructures of the LSCF layer, including porosity and thickness per printing scan cycle, are adjusted by grayscale in the printing image. It is successfully demonstrated that anode-supported SOFCs with optimally printed LSCF cathodes can produce decent power output, i.e., a maximum peak power density of 377 mW cm-2 at 600 °C, in our experiment. We expect that this approach can support the quick and easy prototyping and evaluating of a variety of cathode materials in SOFC research.

  5. The influence of cobalt/vitamin B12 deficiency as a "stressor" affecting adrenal cortex and ovarian activities in goats.

    PubMed

    Mgongo, F O; Gombe, S; Ogaa, J S

    1984-01-01

    Twenty 1.5 to 2-year old goats were made vitamin B12 deficient by feeding them cobalt-deficient diets for 23 weeks in order to determine the effects of a progressive deficiency on ovarian and adrenal cortex activities. At 1-day intervals, blood samples were collected for haematological study and plasma for vitamin B12, progesterone and corticosteroid radioimmunoassays. At 23 weeks, the adrenal cortex was taken for histological measurement and the pituitary gland and corpus luteum for LH and progesterone determinations, respectively. The regularity of the oestrous cycles was studied using teaser bucks. The goats receiving a cobalt-deficient diet presented irregular oestrous cycles (22.6 +/- 0.8 days; maximum deviation: 12 to 38 days), while those of the controls were 18 +/- 0.3 days (maximum deviation: 16 to 21 days). Low vitamin B12 concentration led to macrocytic and normochromic anaemia. The concentration of plasma progesterone augmented, but it decreased during the third and subsequent cycles in cobalt-deficient goats as compared to the controls. Plasma corticosteroids were persistently high in cobalt-deficient goats as compared to the controls, and pituitary LH was low in the deficient goats. It is suggested that an erratic endocrinological control mechanism led to irregular cycles, the action site being located in the hypothalamo-pituitary axis.

  6. Mössbauer spectroscopy, magnetic characteristics, and reflection loss analysis of nickel-strontium substituted cobalt ferrite nanoparticles

    SciTech Connect

    Ghasemi, Ali; Paesano, Andrea; Cerqueira Machado, Carla Fabiana; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

    2014-05-07

    In current research work, Co{sub 1-x}Ni{sub x/2}Sr{sub x/2}Fe{sub 2}O{sub 4} (x = 0–1 in a step of 0.2) ferrite nanoparticles were synthesized by a sol-gel method. According to the evolution in the subspectral areas obtained from Mössbauer spectroscopy, it was found that the relaxing iron belongs mostly to the site B, since the Mössbauer fraction of site A does not vary appreciably. With an increase in Ni-Sr substitution contents in cobalt ferrite, the coercivity and saturation of magnetization decrease. Variation of reflection loss versus frequency in microwave X-band demonstrates that the reflection peak shifts to lower frequency by adding substituted cations and the synthesized nanoparticles can be considered for application in electromagnetic wave absorber technology.

  7. Colossal positive magnetoresistance in surface-passivated oxygen-deficient strontium titanite

    PubMed Central

    David, Adrian; Tian, Yufeng; Yang, Ping; Gao, Xingyu; Lin, Weinan; Shah, Amish B.; Zuo, Jian-Min; Prellier, Wilfrid; Wu, Tom

    2015-01-01

    Modulation of resistance by an external magnetic field, i.e. magnetoresistance effect, has been a long-lived theme of research due to both fundamental science and device applications. Here we report colossal positive magnetoresistance (CPMR) (>30,000% at a temperature of 2 K and a magnetic field of 9 T) discovered in degenerate semiconducting strontium titanite (SrTiO3) single crystals capped with ultrathin SrTiO3/LaAlO3 bilayers. The low-pressure high-temperature homoepitaxial growth of several unit cells of SrTiO3 introduces oxygen vacancies and high-mobility carriers in the bulk SrTiO3, and the three-unit-cell LaAlO3 capping layer passivates the surface and improves carrier mobility by suppressing surface-defect-related scattering. The coexistence of multiple types of carriers and inhomogeneous transport lead to the emergence of CPMR. This unit-cell-level surface engineering approach is promising to be generalized to others oxides, and to realize devices with high-mobility carriers and interesting magnetoelectronic properties. PMID:25975606

  8. Predicted risk of cobalt deficiency in grazing sheep from a geochemical survey; communicating uncertainty with the IPCC verbal scale.

    NASA Astrophysics Data System (ADS)

    Lark, R. M.; Ander, E. L.; Cave, M. R.; Knights, K. V.; Glennon, M. M.; Scanlon, R. P.

    2014-05-01

    Deficiency or excess of certain trace elements in the soil causes problems for agriculture, including disorders of grazing ruminants. Farmers and their advisors in Ireland use index values for the concentration of total soil cobalt and manganese to identify where grazing sheep are at risk of cobalt deficiency. We used cokriging with topsoil data from a regional geochemical survey across six counties of Ireland to form local cokriging predictions of cobalt and manganese concentrations with an attendant distribution which reflects the joint uncertainty of these predictions. From this distribution we then computed conditional probabilities for different combinations of cobalt and manganese index values, and so for the corresponding inferred risk to sheep of cobalt deficiency and the appropriateness of different management interventions. The challenge is to communicate these results effectively to an audience comprising, inter alia, farmers, agronomists and veterinarians. Numerical probabilities are not generally well-understood by non-specialists. For this reason we presented our results as maps using a verbal scale to communicate the probability that a deficiency is indicated by local soil conditions, or that a particular intervention is indicated. In the light of recent research on the effectiveness of the verbal scale used by the Intergovernmental Panel on Climate Change to communicate probabilistic information we reported the geostatistical predictions as follows. First, we use the basic IPCC scale with intensifiers, but we also indicate the corresponding probabilities (as percentages) as recommended by Budescu et al. (2009). Second, we make it clear that the source of uncertainty in these predictions is the spatial variability of soil Co and Mn. The outcome under consideration is therefore that a particular soil management scenario would be indicated if the soil properties were known without error, possible uncertainty about the implications of particular soil

  9. Trace Element Status (Iron, Zinc, Copper, Chromium, Cobalt, and Nickel) in Iron-Deficiency Anaemia of Children under 3 Years

    PubMed Central

    Angelova, Maria Georgieva; Petkova-Marinova, Tsvetelina Valentinova; Pogorielov, Maksym Vladimirovich; Loboda, Andrii Nikolaevich; Nedkova-Kolarova, Vania Nedkova; Bozhinova, Atanaska Naumova

    2014-01-01

    Aim. To determine trace element status and aetiologic factors for development of trace elements deficiencies in children with iron-deficiency anaemia (IDA) aged 0 to 3 years. Contingent and Methods. 30 patients of the University Hospital, Pleven, Bulgaria—I group; 48 patients of the Sumy Regional Child's Clinical Hospital, Sumy, Ukraine—II group; 25 healthy controls were investigated. Serum concentrations of iron, zinc, copper, chromium, cobalt, and nickel were determined spectrophotometrically and by atomic absorption spectrophotometry. Results. Because the obtained serum levels of zinc, copper, and chromium were near the lower reference limits, I group was divided into IA and IB. In IA group, serum concentrations were lower than the reference values for 47%, 57%, and 73% of patients, respectively. In IB group, these were within the reference values. In II group, results for zinc, cobalt, and nickel were significantly lower (P < 0.05), and results for copper were significantly higher in comparison to controls. Conclusion. Low serum concentrations of zinc, copper, cobalt, and nickel were mainly due to inadequate dietary intake, malabsorption, and micronutrient interactions in both studied groups. Increased serum copper in II group was probably due to metabolic changes resulting from adaptations in IDA. Data can be used for developing a diagnostic algorithm for IDA. PMID:24839556

  10. Process for strontium-82 separation

    DOEpatents

    Heaton, Richard C.; Jamriska, Sr., David J.; Taylor, Wayne A.

    1992-01-01

    A process for selective separation of strontium-82 and strontium-85 from proton irradiated molybdenum targets comprises dissolving the molybdenum target in a hydrogen peroxide solution to form a first solution containing ions selected from a group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium, rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, and yttrium; passing the solution through a first cationic resin whereby ions selected from a group consisting of zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium a portion of zirconium and a portion of rubidium are selectively absorbed by the first resin; contacting the first resin with an acid solution to strip and remove the absorbed ions from the first cationic exchange resin to form a second solution; evaporating the second solution for a time sufficient to remove substantially all of the acid and water from the solution whereby a residue remains; dissolving the residue in a dilute acid to form a third solution; passing the third solution through a second cationic resin whereby the ions are absorbed by the second resin; contacting the second resin with a dilute sulfuric acid solution whereby the absorbed ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium and zirconium are selectively removed from the second resin; and contacting the second resin with a dilute acid solution whereby the absorbed strontium ions are selectively removed.

  11. Process for strontium-82 separation

    DOEpatents

    Heaton, R.C.; Jamriska, D.J. Sr.; Taylor, W.A.

    1992-12-01

    A process for selective separation of strontium-82 and strontium-85 from proton irradiated molybdenum targets comprises dissolving the molybdenum target in a hydrogen peroxide solution to form a first solution containing ions selected from a group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium, rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, and yttrium; passing the solution through a first cationic resin whereby ions selected from a group consisting of zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium a portion of zirconium and a portion of rubidium are selectively absorbed by the first resin; contacting the first resin with an acid solution to strip and remove the absorbed ions from the first cationic exchange resin to form a second solution; evaporating the second solution for a time sufficient to remove substantially all of the acid and water from the solution whereby a residue remains; dissolving the residue in a dilute acid to form a third solution; passing the third solution through a second cationic resin whereby the ions are absorbed by the second resin; contacting the second resin with a dilute sulfuric acid solution whereby the absorbed ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium and zirconium are selectively removed from the second resin; and contacting the second resin with a dilute acid solution whereby the absorbed strontium ions are selectively removed. 1 fig.

  12. Lattice dynamics of cobalt-deficient CoO from first principles

    NASA Astrophysics Data System (ADS)

    Wdowik, U. D.; Parlinski, K.

    2008-12-01

    Ab initio calculated Hellmann-Feynman forces were used to investigate an influence of vacancies on the lattice dynamics of a charge-transfer insulator CoO. Electron correlations were taken into account by applying the Hubbard potential U and the exchange interaction J . Vacancies of concentrations of 3% and 6% were introduced into the cobalt sublattice. For structures with defects the phonon density of states and the phonon-dispersion relations were calculated. Vacancies influence predominantly the optical phonon vibrations. The increasing nonstoichiometry decreases the TO frequencies and increases the LO frequencies, while the long-wavelength acoustic phonons do not experience changes. The mean-squared vibrational amplitudes of both cobalt and oxygen increase with the increasing concentration of cobalt vacancies. Results of the calculations are compared to the existing experimental data.

  13. Magnetism and Faraday Rotation in Oxygen-Deficient Polycrystalline and Single-Crystal Iron-Substituted Strontium Titanate

    NASA Astrophysics Data System (ADS)

    Goto, Taichi; Kim, Dong Hun; Sun, Xueyin; Onbasli, Mehmet C.; Florez, Juan M.; Ong, Shyue Ping; Vargas, Patricio; Ackland, Karl; Stamenov, Plamen; Aimon, Nicolas M.; Inoue, Mitsuteru; Tuller, Harry L.; Dionne, Gerald F.; Coey, J. Michael D.; Ross, Caroline A.

    2017-02-01

    Both polycrystalline and single-crystal films of iron-substituted strontium titanate, Sr (Ti0.65Fe0.35)O3 -δ , prepared by pulsed laser deposition, show room-temperature magnetism and Faraday rotation, with the polycrystalline films exhibiting higher saturation magnetization and Faraday rotation. The magnetic properties vary with the oxygen pressure at which the films are grown, showing a maximum at pressures of approximately 4 μ Torr at which the unit-cell volume is largest. The results are discussed in terms of the oxygen stoichiometry and corresponding Fe valence states, the structure and strain state, and the presence of small-volume fractions of metallic Fe in single-crystal films grown at the optimum deposition pressure. Integration of magneto-optical polycrystalline films on an optical-waveguide device demonstrates a nonreciprocal phase shift.

  14. Surface redox properties of lanthanum chromium nickel oxide, lanthanum strontium cobalt oxide, and silver explored via in-situ x-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Vovk, Gregory

    The surface redox properties of LaCr0.6Ni0.4O 3 (powder), La0.5Sr0.5CoO3 (thin film) and silver (powder) were investigated using X-ray photoelectron spectroscopy (XPS). In order to control the oxidation state of a sample in ultra high vacuum (UHV) conditions, it was incorporated as the working electrode in a solid state electrochemical cell with the following configuration: (sample|YSZ|Pd:PdO)), where YSZ is 8 mol% yttria-stabilized zirconia, an oxide ion conducting electrolyte and Pd:PdO is a palladium-palladium oxide powder mixture serving as the reference electrode and an oxygen reservoir. Reduction/oxidation of the sample was initiated by applying an external bias voltage to the sample. It was found that the surface of LaCr0.6Ni0.4O 3 and LaNiO3 powders could be reversibly reduced and oxidized electrochemically to changes involving La, Cr, Ni, and to a lesser extent, O surface atoms. Binding energy shifts (with respect to the La 3d5/2 peak) were seen for the Cr 2p, Ni 3p, and O 1s peaks. The La 3d peaks did not shift noticeably upon reduction, but did exhibit La 3d5/2 parent:satellite ratio changes. The reduced surfaces of LaCr0.6Ni 0.4O3 and LaNiO3 were found to be active in adsorbing CO2, an indication of the increased Lewis basicity of these surfaces upon electrochemical reduction. La0.5Sr0.5CoO3 thin films displayed similar La 3d5/2 parent:satellite ratio changes as to those seen on LaCr0.6Ni0.4O3 and LaNiO3. The electronic behavior of the B-cation, Co, showed localized electronic changes. Furthermore, the surface stoichiometry of La0.5Sr0.5CoO 3 was rich in La and Sr and displayed irreversible binding energy changes in the Sr 3d and O 1s XPS signals. Two different species of oxygen and strontium were always present on the La0.5Sr0.5CoO3 surface. Ag showed reversible changes to O 1s XPS binding energy shifts and amounts. Although this behavior is in agreement with previous reports, the results were complicated by the reversible movement of sodium arising

  15. Oxides of LANTHANUM(1-X) Strontium(x) COBALT(1 - Iron(y) OXYGEN(3) for Oxygen and Electrical Delivery Systems

    NASA Astrophysics Data System (ADS)

    Tai, Lone-Wen Frank

    Perovskite-type compounds in the system La_{1-x}Sr_{x}Co _{1-y}Fe_{y}O_ {3-delta have been considered as potential cathode materials for solid oxide fuel cells. The purpose of this study was to evaluate the structural, electrical, thermochemical properties of these compositions. The first and second papers of this dissertation dealt with the material synthesis, crystal structure, thermal expansion, thermogravimetry, electrical conductivity, and thermoelectricity of La_{0.8 }Sr_{0.2}Co_{1-y}Fe _{y}O_3 (y = 0-1) and La_{1-x}Sr_{x}Co _{0.2}Fe_{0.8}O_3 (x = 0-1) in air, respectively. Electrical conductivities and thermal expansion coefficients for these compositions were found to increase with Sr and Co contents. The unique temperature and composition dependence of the electrical conductivity observed in both systems were semi-empirically modeled by incorporating several mechanisms which include the hopping conduction of small polarons, a thermally activated charge disproportionation of Co^{3+ }, the ionic compensation by oxygen vacancy, and a preferential electronic compensation of acceptor by forming Fe^{4+} over Co^{4+}.. Phase stability, oxygen content, electrical conductivity, and Seebeck coefficient of La_ {1-x}Sr_{x}Co_{0.2 }Fe_{0.8}O_{3-delta } (x = 0, 0.2, 0.4) as function of temperature and oxygen activity were reported in the third paper. Both the oxygen deficiency and phase stability of compositions with y = 0.8 were found considerably high. It has been demonstrated that the degree of oxygen deficiency in these compositions significantly influences their structural and electrical properties, especially in the high temperature region.

  16. Handbook of stable strontium

    SciTech Connect

    Skoryna, S.C.

    1981-01-01

    This book presents information on the following topics: chemistry of strontium; biogeochemistry of strontium; uptake of stable strontium by plants and effects on plant growth; divalent cation-dependent deposits in paramecium; effects of strontium ion on the hydrolysis of ATP; stronium ions and membranes - screening versus binding at charged surfaces; mitochondrial granules in the liver of rats kept on stable strontium supplementation; divalent cations and regulation of cyclic nucleotides in nervous systems; strontium as the substitute for calcium in the excitation-contraction coupling of crayfish muscle fibers; hemodynamic effects of strontium in the dog; some mechanical characteristics of strontium-mediated contractions in heart muscle; effects of calcium, magnesium, and strontium on drug-receptor interactions; strontium and histamine secretion; and effects of strontium in human dental enamel.

  17. Defect equilibria and chemical expansion in undoped and doped ceria and strontium doped lanthanum cobalt iron oxide oxygen conducting materials and their applications in solid-state electrochemical cells

    NASA Astrophysics Data System (ADS)

    Bishop, Sean R.

    Ceramic oxygen conducting materials are used in many energy-related applications from fuel reforming to electricity generation. In a typical ceramic oxygen conductor, oxygen ions are transmitted through a dense membrane via defects in the material. Hence, defects control the performance of these materials. In low oxygen partial pressure, ceria based materials become non-stoichiometric and can form defect complexes that hinder ionic conductivity. In addition, oxygen non-stoichiometry induces strain (chemical expansion) that can result in stresses for composite or constrained applications. In this dissertation the non-stoichiometry and chemical expansion behavior is reported as a function of PO2 for undoped ceria, gadolinium doped ceria (GDC) and strontium doped lanthanum cobalt iron oxide (LSCF). Undoped ceria was measured at 800°C and GDC and LSCF at 600--900°C in a wide PO2 range. It was found that defect interactions could effectively be modeled in ceria based materials using defect complex formation in a mass action formalism and the results were used to model nonlinear chemical expansion behavior. In LSCF, non-stoichiometry and chemical expansion were modeled using using metallic and semi-conductor models. A semi-conductor model with B-site small polarons best represented the measured behavior. The resulting models and parameters can be used to predict mechanical and electrical behavior of SOFC components. Surface oxygen non-stoichiometry has also been measured by comparing low surface area to high surface area samples. It was found that surface defect concentration previously ignored in the literature can result in erroneous non-stoichiometry measurements. In the latter half of this dissertation these materials are applied in SOFC and ceramic oxygen generator (COG) technology. A strategy is presented here for advanced life support systems employs a catalytic layer combined with a COG cell so that CO2 is reduced all the way to solid carbon and oxygen without

  18. Strontium Concentrations in Corrosion Products from Residential Drinking Water Distribution Systems

    DTIC Science & Technology

    2013-04-22

    incorporation of cobalt and/or strontium into pipe deposits within a distribution system could result in mobilization of these metals into Figure 4...2007, 41 (2), 387−96. (9) Toxicological Profile for Strontium; Agency for Toxic Substances and Disease Registry: Atlanta, GA, 2004. (10) US EPA...calcium (Ca2+). Strontium readily substitutes for Ca2+ in the metal site (M1) of minerals and in the structure of bone.1 The most common Sr2

  19. Diastereoselective Radical‐Type Cyclopropanation of Electron‐Deficient Alkenes Mediated by the Highly Active Cobalt(II) Tetramethyltetraaza[14]annulene Catalyst

    PubMed Central

    Chirila, Andrei; Gopal Das, Braja; Paul, Nanda D.

    2017-01-01

    Abstract A new protocol for the catalytic synthesis of cyclopropanes using electron‐deficient alkenes is presented, which is catalysed by a series of affordable, easy to synthesise and highly active substituted cobalt(II) tetraaza[14]annulenes. These catalysts are compatible with the use of sodium tosylhydrazone salts as precursors to diazo compounds in one‐pot catalytic transformations to afford the desired cyclopropanes in almost quantitative yields. The reaction takes advantage of the metalloradical character of the Co complexes to activate the diazo compounds. The reaction is practical and fast, and proceeds from readily available starting materials. It does not require the slow addition of diazo reagents or tosylhydrazone salts or heating and tolerates many solvents, which include protic ones such as MeOH. The CoII complexes derived from the tetramethyltetraaza[14]annulene ligand are easier to prepare than cobalt(II) porphyrins and present a similar catalytic carbene radical reactivity but are more active. The reaction proceeds at 20 °C in a matter of minutes and even at −78 °C in a few hours. The catalytic system is robust and can operate with either the alkene or the diazo reagent as the limiting reagent, which inhibits the dimerisation of diazo compounds totally. The protocol has been applied to synthesise a variety of substituted cyclopropanes. High yields and selectivities were achieved for various substrates with an intrinsic preference for trans cyclopropanes. PMID:28529668

  20. [Distribution iodine deficiency diseases in coastal areas depending on geochemical conditions].

    PubMed

    Kiku, P F; Andryukov, B G

    2014-01-01

    In the Primorsky Krai there was performed a population ecological and hygienic analysis of the relationship between the content of chemical elements in the soil and thyroid morbidity in the population of the region. The assessment of the prevalence of iodine deficiency and iodine deficiency diseases was carried out on the basis of the impact of the priority environmental toxic (strontium, nickel, cadmium, lead, arsenic, tin) and essential (nickel, iron, germanium, molybdenum, zinc, selenium) trace elements on the level of iodine deficiency diseases. The level of thyroid pathology in the territory of Primorye was established to be the highest one in areas characterized by the severe iodine deficiency (Northwest geochemical zones), where the structure of thyroid diseases is presented mainly by diffuse nontoxic goiter. Thyroid diseases associated with iodine deficiency in the population of different age groups are the result of multiple and combined imbalance of trace elements, which causes a relative (secondary) iodine deficiency. Thyroid disease in Primorye are environmentally caused diseases of technogenic origin, they are a consequence of the relative iodine deficiency, when on the background of normal iodine supply an imbalance of zinc, iron, cobalt, manganese with excess of such toxic trace elements as lead, strontium, nickel and chromium takes place. Thyroid pathology associated with iodine deficiency, along with other environmentally dependent diseases can be considered as a marker of ecological environment trouble.

  1. The effects of strontium ranelate treatment on ovariectomized Sprague-Dawley rat tibia

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Jin, W.; Wang, C.; Yang, M.; Shen, H.; Eisa, M. H.; Mi, Y.

    2009-06-01

    Micro Proton Induced X-ray Emission (micro-PIXE) technique was used to study the effect of strontium ranelate on osteoporosis resulted from estrogen deficiency. The contents of calcium and strontium in tibia, as well as calcium distribution for structural determination were investigated. Three groups of tibia samples were respectively taken from three groups of female Sprague-Dawley (S.D.) rats, i.e. control, ovariectomized and ovariectomized followed strontium ranelate treatment. It was found that the strontium content was decreasing in the bone from ovariectomized rat compared with that in control, but significantly increasing in the bone from strontium ranelate treated ovariectomized rat. Our study showed that strontium content is a feasible parameter for the diagnosis of osteoporosis caused by estrogen deficiency. Strontium ranelate is an effective antiosteoporosis chemical to rebuild the bone structure and prevent deterioration of bone strength as well.

  2. Mineral resource of the month: Strontium

    USGS Publications Warehouse

    Ober, Joyce A.

    2014-01-01

    Strontium occurs commonly in nature, ranking as the 15th most abundant chemical element on Earth. Only two minerals contain sufficient strontium, however, to be used commercially to produce strontium compounds: Strontianite (strontium carbonate) has a higher strontium content, but celestite (strontium sulfate) is by far the most abundant strontium mineral.

  3. Strontium-89 Chloride

    MedlinePlus

    ... ever had bone marrow disease, blood disorders, or kidney disease.you should know that strontium-89 chloride may interfere with the normal menstrual cycle (period) in women and may stop sperm production ...

  4. Recovery of strontium activity from a strontium-82/rubidium-82 generator

    DOEpatents

    Taylor, Wayne A.; Phillips, Dennis R.; Sosnowski, Kenneth M.

    1999-10-12

    Strontium-82 is recovered from spent strontium-82/rubidium-82 generators to provide a source of strontium-82 for additional strontium-82/rubidium-82 generators. The process involves stripping of the strontium-82 from used strontium-82/rubidium-82 generators followed by purification of the strontium-82 material to remove additional metal contaminants to desired levels.

  5. Cobalt poisoning

    MedlinePlus

    ... the wear and tear of some cobalt/chromium metal-on-metal hip implants. This type of implant is an ... hip socket that is created by fitting a metal ball into a metal cup. Sometimes, metal particles ( ...

  6. [Strontium ranelate: a novel concept for the treatment of osteoporosis].

    PubMed

    Dimai, Hans Peter

    2005-11-01

    The di-strontium salt strontium ranelate, a novel orally active agent consisting of two atoms of stable strontium and the organic moiety ranelic acid, has been developed for the treatment of osteoporosis. It has been shown to enhance osteoblastic cell replication and increase collagen synthesis while decreasing pre-osteoclast differentiation and bone-resorbing activity of mature osteoclasts in vitro. Studies performed in healthy animals have shown that strontium ranelate not only increases bone mass at various skeletal sites but also improves mechanical properties of femoral, humeral and vertebral bones. In estrogen-deficient animals, strontium ranelate effectively inhibits increased bone resorption while maintaining bone formation. Similar results have been obtained from studies in hind limb-immobilized animals. Strontium ranelate has been investigated in a large phase III program which includes two extensive multinational, randomized, double-blind, placebo-controlled clinical trials for the treatment of severe postmenopausal osteoporosis. Before inclusion in these two studies, patients were subjected to a run-in study in order to initiate normalization of their calcium and vitamin D status. The SOTI study, aimed at assessing strontium ranelate's effect on the risk of vertebral fractures, revealed a significant reduction in the risk of new vertebral fractures in the group treated with strontium ranelate. The TROPOS study, which aimed at evaluating the effect of strontium ranelate on nonvertebral fractures, showed a significant reduction in the risk of new nonvertebral fractures and also, in a high-risk subgroup, a significant reduction in the risk of hip fractures. In both studies, the reduction in fracture risk was accompanied by an increase in bone mineral density. The increase remained significant also after correction of the bone mineral density for the higher atomic mass of strontium compared to calcium. Furthermore, an increase in serum levels of a bone

  7. Preparation and use of polymeric materials containing hydrophobic anions and plasticizers for separation of cesium and strontium

    DOEpatents

    Abney, K.D.; Kinkead, S.A.; Mason, C.F.V.; Rais, J.

    1997-09-09

    Preparation and use is described for polymeric materials containing hydrophobic anions and plasticizers for extraction of cesium and strontium. The use of polymeric materials containing plasticizers which are solvents for hydrophobic anions such as derivatives of cobalt dicarbollide or tetraphenylborate which are capable of extracting cesium and strontium ions from aqueous solutions in contact with the polymeric materials, is described. The polymeric material may also include a synergistic agent for a given ion like polyethylene glycol or a crown ether, for removal of radioactive isotopes of cesium and strontium from solutions of diverse composition and, in particular, for solutions containing large excess of sodium nitrate.

  8. Preparation and use of polymeric materials containing hydrophobic anions and plasticizers for separation of cesium and strontium

    DOEpatents

    Abney, Kent D.; Kinkead, Scott A.; Mason, Caroline F. V.; Rais, Jiri

    1997-01-01

    Preparation and use of polymeric materials containing hydrophobic anions and plasticizers for extraction of cesium and strontium. The use of polymeric materials containing plasticizers which are solvents for hydrophobic anions such as derivatives of cobalt dicarbollide or tetraphenylborate which are capable of extracting cesium and strontium ions from aqueous solutions in contact with the polymeric materials, is described. The polymeric material may also include a synergistic agent for a given ion like polyethylene glycol or a crown ether, for removal of radioactive isotopes of cesium and strontium from solutions of diverse composition and, in particular, for solutions containing large excess of sodium nitrate.

  9. Cobalt superalloy

    SciTech Connect

    Crook, P.

    1983-11-15

    Disclosed is a cobalt-base superalloy containing about 32% cobalt, 8% nickel, 26.5% chromium, 2.5% tungsten, 5% niobium, about 1% each manganese and silicon, about 0.4% carbon, and the balance about 23% iron plus incidental impurities and modifiers normally found in alloys of this class. The alloy is readily processed in the form of wrought products, castings, metal powder and all forms of welding and hardfacing materials. The outstanding characteristics of the new alloy include the resistance to cavitation erosion and galling, low cost and minimal use of strategic metals.

  10. Accumulation of bone strontium measured by in vivo XRF in rats supplemented with strontium citrate and strontium ranelate.

    PubMed

    Wohl, Gregory R; Chettle, David R; Pejović-Milić, Ana; Druchok, Cheryl; Webber, Colin E; Adachi, Jonathan D; Beattie, Karen A

    2013-01-01

    Strontium ranelate is an approved pharmacotherapy for osteoporosis in Europe and Australia, but not in Canada or the United States. Strontium citrate, an alternative strontium salt, however, is available for purchase over-the-counter as a nutritional supplement. The effects of strontium citrate on bone are largely unknown. The study's objectives were 1) to quantify bone strontium accumulation in female Sprague Dawley rats administered strontium citrate (N=7) and compare these levels to rats administered strontium ranelate (N=6) and vehicle (N=6) over 8 weeks, and 2) to verify an in vivo X-ray fluorescence spectroscopy (XRF) system for measurement of bone strontium in the rat. Daily doses of strontium citrate and strontium ranelate were determined with the intention to achieve equivalent amounts of elemental strontium. However, post-hoc analyses of each strontium compound conducted using energy dispersive spectrometry microanalysis revealed a higher elemental strontium concentration in strontium citrate than strontium ranelate. Bone strontium levels were measured at baseline and 8 weeks follow-up using a unique in vivo XRF technique previously used in humans. XRF measurements were validated against ex vivo measurements of bone strontium using inductively coupled plasma mass spectrometry. Weight gain in rats in all three groups was equivalent over the study duration. A two-way ANOVA was conducted to compare bone strontium levels amongst the three groups. Bone strontium levels in rats administered strontium citrate were significantly greater (p<0.05) than rats administered strontium ranelate and vehicle. ANCOVA analyses were performed with Sr dose as a covariate to account for differences in strontium dosing. The ANCOVA revealed differences in bone strontium levels between the strontium groups were not significant, but that bone strontium levels were still very significantly greater than vehicle.

  11. Effect of cobalt on the primary productivity of Spirulina platensis

    SciTech Connect

    Sharma, R.M.; Panigrahi, S.; Azeez, P.A.

    1987-10-01

    Cobalt, a micronutrient for biological organisms, is a metal of wide use. Main sources of Co to the environment are combustion of fossil fuels, smelters, cobalt processing facilities, sewage and industrial wastes. Atomic power plants and nuclear weapon detonations form an important source of radioisotopes of this metal to the environment. Cobalt has been included in the 14 toxic trace elements of critical importance from the point of view of environmental pollution and health hazards. Cobalt deficiency leads to diseases like stunted growth. At toxic level, Co inhibits heme biosynthesis and enzyme activities. The present study reports the effect of cobalt on biomass productivity of blue-green alga Spirulina platensis.

  12. ADVANCED TECHNOLOGIES FOR THE SIMULTANEOUS SEPARATION OF CESIUM AND STRONTIUM FROM SPENT NUCLEAR FUEL

    SciTech Connect

    Jack D. Law; Terry A. Todd; R. Scott Herbst; David H. Meikrantz; Dean R. Peterman; Catherine L. Riddle; Richard D. Tillotson

    2005-02-01

    Two new solvent extraction technologies have been recently developed to simultaneously separate cesium and strontium from spent nuclear fuel, following dissolution in nitric acid. The first process utilizes a solvent consisting of chlorinated cobalt dicarbollide and polyethylene glycol extractants in a phenyltrifluoromethyl sulfone diluent. Recent improvements to the process include development of a new, non-nitroaromatic diluent and development of new stripping reagents, including a regenerable strip reagent that can be recovered and recycled. This new strip reagent reduces product volume by a factor of 20, over the baseline process. Countercurrent flowsheet tests on simulated spent nuclear fuel feed streams have been performed with both cesium and strontium removal efficiencies of greater than 99 %. The second process developed to simultaneously separate cesium and strontium from spent nuclear fuel is based on two highly-specific extractants: 4',4',(5')-Di-(t-butyldicyclo-hexano)-18-crown-6 (DtBuCH18C6) and Calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6). The DtBuCH18C6 extractant is selective for strontium and the BOBCalixC6 extractant is selective for cesium. A solvent composition has been developed that enables both elements to be removed together and, in fact, a synergistic effect was observed with strontium distributions in the combined solvent that are much higher that in the strontium extraction (SREX) process. Initial laboratory test results of the new combined cesium and strontium extraction process indicate good extraction and stripping performance.

  13. Strontium ranelate discontinued.

    PubMed

    2017-08-02

    Strontium ranelate discontinued ● Limited treatment options for molluscum contagiosum ● Finasteride drug safety alert ● Does doxycycline delay the next COPD exacerbation? ● Support for WHO standards on reporting clinical trial results ● Delayed antibiotic prescription for lower respiratory tract infections ● Nystatin dose change - much ado about nothing? Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  14. High-level production of ethylmalonyl-CoA pathway-derived dicarboxylic acids by Methylobacterium extorquens under cobalt-deficient conditions and by polyhydroxybutyrate negative strains.

    PubMed

    Sonntag, Frank; Müller, Jonas E N; Kiefer, Patrick; Vorholt, Julia A; Schrader, Jens; Buchhaupt, Markus

    2015-04-01

    Bio-based production of dicarboxylic acids is an emerging research field with remarkable progress during the last decades. The recently established synthesis of the ethylmalonyl-CoA pathway (EMCP)-derived dicarboxylic acids, mesaconic acid and (2S)-methylsuccinic acid, from the alternative carbon source methanol (Sonntag et al., Appl Microbiol Biotechnol 98:4533-4544, 2014) gave a proof of concept for the sustainable production of hitherto biotechnologically inaccessible monomers. In this study, substantial optimizations of the process by different approaches are presented. Abolishment of mesaconic and (2S)-methylsuccinic acid reuptake from culture supernatant and a productivity increase were achieved by 30-fold decreased sodium ion availability in culture medium. Undesired flux from EMCP into polyhydroxybutyrate (PHB) cycle was hindered by the knockout of polyhydroxyalkanoate synthase phaC which was concomitant with 5-fold increased product concentrations. However, frequently occurring suppressors of strain ΔphaC lost their beneficial properties probably due to redirected channeling of acetyl-CoA. Pool sizes of the product precursors were increased by exploiting the presence of two cobalt-dependent mutases in the EMCP: Fine-tuned growth-limiting cobalt concentrations led to 16-fold accumulation of mesaconyl- and (2S)-methylsuccinyl-CoA which in turn resulted in 6-fold increased concentrations of mesaconic and (2S)-methylsuccinic acids, with a combined titer of 0.65 g/l, representing a yield of 0.17 g/g methanol. This work represents an important step toward an industrially relevant production of ethylmalonyl-CoA pathway-derived dicarboxylic acids and the generation of a stable PHB synthesis negative Methylobacterium extorquens strain.

  15. Effect of cobalt on parameters of the cardiovascular system in elementary school children.

    PubMed

    Svyatova, N V; Sitdikov, F G; Egerev, E S

    2013-07-01

    High incidence of cobalt deficiency (89%) was found in 7-8-year-old girls residents of the Republic of Tatarstan. Significant correlations were revealed between parameters of physical development and cardiovascular system and hair cobalt content. These data suggest that positive balance of cobalt is essential for normal growth and development of child's body and function of the cardiovascular system.

  16. Presynaptic strontium dynamics and synaptic transmission.

    PubMed

    Xu-Friedman, M A; Regehr, W G

    1999-04-01

    Strontium can replace calcium in triggering neurotransmitter release, although peak release is reduced and the duration of release is prolonged. Strontium has therefore become useful in probing release, but its mechanism of action is not well understood. Here we study the action of strontium at the granule cell to Purkinje cell synapse in mouse cerebellar slices. Presynaptic residual strontium levels were monitored with fluorescent indicators, which all responded to strontium (fura-2, calcium orange, fura-2FF, magnesium green, and mag-fura-5). When calcium was replaced by equimolar concentrations of strontium in the external bath, strontium and calcium both entered presynaptic terminals. Contaminating calcium was eliminated by including EGTA in the extracellular bath, or by loading parallel fibers with EGTA, enabling the actions of strontium to be studied in isolation. After a single stimulus, strontium reached higher peak free levels than did calcium (approximately 1.7 times greater), and decayed more slowly (half-decay time 189 ms for strontium and 32 ms for calcium). These differences in calcium and strontium dynamics are likely a consequence of greater strontium permeability through calcium channels, lower affinity of the endogenous buffer for strontium, and less efficient extrusion of strontium. Measurements of presynaptic divalent levels help to explain properties of release evoked by strontium. Parallel fiber synaptic currents triggered by strontium are smaller in amplitude and longer in duration than those triggered by calcium. In both calcium and strontium, release consists of two components, one more steeply dependent on divalent levels than the other. Strontium drives both components less effectively than does calcium, suggesting that the affinities of the sensors involved in both phases of release are lower for strontium than for calcium. Thus, the larger and slower strontium transients account for the prominent slow component of release triggered by

  17. Presynaptic strontium dynamics and synaptic transmission.

    PubMed Central

    Xu-Friedman, M A; Regehr, W G

    1999-01-01

    Strontium can replace calcium in triggering neurotransmitter release, although peak release is reduced and the duration of release is prolonged. Strontium has therefore become useful in probing release, but its mechanism of action is not well understood. Here we study the action of strontium at the granule cell to Purkinje cell synapse in mouse cerebellar slices. Presynaptic residual strontium levels were monitored with fluorescent indicators, which all responded to strontium (fura-2, calcium orange, fura-2FF, magnesium green, and mag-fura-5). When calcium was replaced by equimolar concentrations of strontium in the external bath, strontium and calcium both entered presynaptic terminals. Contaminating calcium was eliminated by including EGTA in the extracellular bath, or by loading parallel fibers with EGTA, enabling the actions of strontium to be studied in isolation. After a single stimulus, strontium reached higher peak free levels than did calcium (approximately 1.7 times greater), and decayed more slowly (half-decay time 189 ms for strontium and 32 ms for calcium). These differences in calcium and strontium dynamics are likely a consequence of greater strontium permeability through calcium channels, lower affinity of the endogenous buffer for strontium, and less efficient extrusion of strontium. Measurements of presynaptic divalent levels help to explain properties of release evoked by strontium. Parallel fiber synaptic currents triggered by strontium are smaller in amplitude and longer in duration than those triggered by calcium. In both calcium and strontium, release consists of two components, one more steeply dependent on divalent levels than the other. Strontium drives both components less effectively than does calcium, suggesting that the affinities of the sensors involved in both phases of release are lower for strontium than for calcium. Thus, the larger and slower strontium transients account for the prominent slow component of release triggered by

  18. High-resolution stratigraphy with strontium isotopes.

    PubMed

    Depaolo, D J; Ingram, B L

    1985-02-22

    The isotopic ratio of strontium-87 to strontium-86 shows no detectable variation in present-day ocean water but changes slowly over millions of years. The strontium contained in carbonate shells of marine organisms records the ratio of strontium-87 to strontium-86 of the oceans at the time that the shells form. Sedimentary rocks composed of accumulated fossil carbonate shells can be dated and correlated with the use of high precision measurements of the ratio of strontium-87 to strontium-86 with a resolution that is similar to that of other techniques used in age correlation. This method may prove valuable for many geological, paleontological, paleooceanographic, and geochemical problems.

  19. Strontium ranelate in osteoporosis.

    PubMed

    Reginster, J-Y

    2002-01-01

    Strontium ranelate is composed of an organic moiety (ranelic acid) and of two atoms of stable non-radioactive strontium. In vitro, strontium ranelate increases collagen and non-collagenic proteins synthesis by mature osteoblast enriched cells. The effects of strontium ranelate on bone formation were confirmed as strontium ranelate enhanced pre-osteoblastic cells replication. The stimulation by strontium ranelate of the replication of osteoprogenitor cells and collagen as well as non-collagenic protein synthesis in osteoblasts provides substantial evidence to categorise SR ranelate as a bone forming agent. In the mouse calvaria culture system, SR ranelate induces a dose-dependent inhibition of labelled calcium release. The inhibitory effects of SR ranelate on bone resorption were close to those of salmon calcitonin. In the isolated rat osteoclast assay, a pre-incubation of bone slices with SR ranelate induced a dose-dependent inhibition of the bone resorbing activity of a treated rat osteoclast. SR ranelate also dose-dependently inhibited, in a chicken bone marrow culture, the expression of both CA II and the alpha-subunit of the vitronectin receptor. These effects showing that SR ranelate significantly affects bone resorption due to direct and/or matrix-mediated inhibition of osteoclast activity and also inhibits osteoclasts differentiation are compatible with the profile of an anti-resorptive drug. In normal rats, administration of SR ranelate induces an improvement in the mechanical properties of the humerus and/or the lumbar vertebra associated with a commensurate increase in bone dimension, shaft and volume. This was not related to any change in the stiffness, suggesting the absence of a mineralisation defect. After oral administration of SR ranelate in humans, the absolute bio-availability of SR ranelate is 27 % after a dose of 2g is given as sachets. The simultaneous intake of SR ranelate and calcium remarkably reduces the bio-availability of SR. SR ranelate

  20. Interferometry with Strontium Ions

    NASA Astrophysics Data System (ADS)

    Jackson, Jarom; Lambert, Enoch; Otterstrom, Nils; Jones, Tyler; Durfee, Dallin

    2014-05-01

    We describe progress on a cold ion matter-wave interferometer. Cold Strontium atoms are extracted from an LVIS. The atoms will be photo-ionized with a two-photon transition to an auto-ionizing state in the continuum. The ions will be split and recombined using stimulated Raman transitions from a pair of diode lasers injection locked to two beams from a master laser which have been shifted up and down by half the hyperfine splitting. We are developing laser instrumentation for this project including a method to prevent mode-hopping by analyzing laser frequency noise, and an inexpensive, robust wavelength meter. Supported by NSF Award No. 1205736.

  1. Bench-scale treatability studies for simulated incinerator scrubber blowdown containing radioactive cesium and strontium

    SciTech Connect

    Coroneos, A.C.; Taylor, P.A.; Arnold, W.D. Jr.; Bostick, D.A.; Perona, J.J.

    1994-12-01

    The purpose of this report is to document the results of bench-scale testing completed to remove {sup 137}Cs and {sup 90}Sr from the Oak Ridge K-25 Site Toxic Substances Control Act (TSCA) Incinerator blowdown at the K-25 Site Central Neutralization Facility, a wastewater treatment facility designed to remove heavy metals and uranium from various wastewaters. The report presents results of bench-scale testing using chabazite and clinoptilolite zeolites to remove cesium and strontium; using potassium cobalt ferrocyanide (KCCF) to remove cesium; and using strontium chloride coprecipitation, sodium phosphate coprecipitation, and calcium sulfate coprecipitation to remove strontium. Low-range, average-range, and high-range concentration blowdown surrogates were used to complete the bench-scale testing.

  2. Thermoelectricity in strontium titanate

    NASA Astrophysics Data System (ADS)

    Scullin, Matthew Leo

    This dissertation treats the synthesis, experimental characterization, thermoelectric properties, potential applications of, and theoretical basis for strontium titanate thermoelectric materials. It is found that doubly-doped strontium titanate, Sr1-xLaxTiO3-d is an efficient n-type thermoelectric material, yielding a dimensionless thermoelectric figure of merit zT higher than other oxides and among the highest of any thermoelectric material in general. The improvement in thermoelectric efficiency of this material over other oxides is attributed in large part to the oxygen vacancy, which increases the electronic effective mass m* and in turn thermopower, increases electrical conductivity through donating electrons, and decreases lattice thermal conductivity. Through proper selection of La and oxygen vacancy doping, m* can be tuned in the material in the range of 2-20 me and thermal conductivity reduced by over a factor of three compared to stoichiometric SrTiO3. The potential applications of thin-film thermoelectrics in energy conversion are explored. In addition, the remarkable oxygen reduction of SrTiO3 single-crystal substrates is reported as resulting from pulsed laser deposition growth of oxide thin-films on their surfaces.

  3. Boron implanted strontium titanate

    NASA Astrophysics Data System (ADS)

    Cooper, C. J. M.

    Single crystals of strontium titanate implanted with boron were found to have highly conductive surface layers. The effects of varying dose from 10 to the 16th power to 10 to the 17th power ions/sq cm, implantation voltage from 50 to 175 keV and annealing conditions on the room temperature surface resistance and Hall mobility are presented. Variation of the implantation voltage did not have a major effect on the sheet resistances obtained by boron implantation of strontium titanate, while dose and annealing conditions have major effects. Doses of 5 x 10 to the 16th power ions/sq cm required annealing on the order of one hour at 500 K for maximum reduction of the room temperature resistance in the implanted layer. Samples implanted with a dose of 1 x 10 to the 17th power ions/sq cm required slightly higher temperatures (approximately 575 K) to obtain a minimum resistance at room temperature. Long term (several weeks) room temperature annealing was found to occur in high dose samples. After one to two months at room temperature followed by an anneal to 575 K, the surface resistances were found to be lower than those produced by the annealing of a freshly implanted sample to 575 K.

  4. Strontium-90 fluoride data sheet

    SciTech Connect

    Fullam, H.T.

    1981-06-01

    This report is a compilation of available data and appropriate literature references on the properties of strontium-90 fluoride and nonradioactive strontium fluoride. The objective of the document is to compile in a single source pertinent data to assist potential users in the development, licensing, and use of /sup 90/SrF/sub 2/-fueled radioisotope heat sources for terrestrial power conversion and thermal applications. The report is an update of the Strontium-90 Fluoride Data Sheet (BNWL-2284) originally issued in April 1977.

  5. Cobalt free maraging steel

    SciTech Connect

    Floreen, S.

    1984-04-17

    The subject invention is directed to ferrous-base alloys, particularly to a cobalt-free maraging steel of novel chemistry characterized by a desired combination of strength and toughness, notwithstanding that cobalt is non-essential.

  6. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... concentrations. 35.2204 Section 35.2204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and strontium-85...

  7. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... concentrations. 35.2204 Section 35.2204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and strontium-85...

  8. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... concentrations. 35.2204 Section 35.2204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and strontium-85...

  9. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... concentrations. 35.2204 Section 35.2204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and strontium-85...

  10. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... concentrations. 35.2204 Section 35.2204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and strontium-85...

  11. Polarization and dipole moments of Co-doped potassium sodium strontium barium niobate crystals

    SciTech Connect

    Xia, H.R.; Wang, C.J.; Yu, H.; Chen, H.C.; Wang, M.

    1997-11-01

    Single crystals of potassium sodium strontium barium niobate (KNSBN) and cobalt-modified KNSBN were prepared using the Czochralski technique. The ferroelectric hysteresis loops and the infrared reflectivity spectra were collected. Compared with the undoped KNSBN crystals, the cobalt-modified crystals have stable hysteresis loops, whose spontaneous polarization is about 0.17C/m{sup 2} and coercive field strength is about 670 V/mm, but those of the undoped KNSBN crystals are about 0.04C/m{sup 2} and 530 V/mm, respectively. The measured infrared reflectivities vary with the orientations of the dipole moments owing to the Co doping. The c axis becomes the most stable orientation of the dipole moments, and the polarization can be locked and does not recede when the cobalt-modified crystals are polarized into a single domain. {copyright} {ital 1997 American Institute of Physics.}

  12. The use of strontium-87/strontium-86 ratios to measure atmospheric transport in forested watersheds

    SciTech Connect

    Graustein, W.C.; Armstrong, R.L.

    1983-01-21

    Strontium-87/strontium-86 ratios indicate the sources of strontium in samples of natural waters, vegetation, and soil material taken from watersheds in the Sangre de Cristo Mountains of New Mexico. More than 75 percent of the strontium in the vegetation is ultimately derived from atmospheric transport and less than 25 percent from the weathering of the underlying rock. Much of the airborne strontium enters the watersheds by impacting on coniferous foliage, but deciduous foliage apparently traps little, if any, strontium-bearing aerosol. The strontium and presumably other nutrients are continuously recycled in a nearly closed system consisting of upper soil horizons, forest litter, and the standing crop of vegetation.

  13. The Use of Strontium-87/Strontium-86 Ratios to Measure Atmospheric Transport into Forested Watersheds

    NASA Astrophysics Data System (ADS)

    Graustein, William C.; Armstrong, Richard L.

    1983-01-01

    Strontium-87/strontium-86 ratios indicate the sources of strontium in samples of natural waters, vegetation, and soil material taken from watersheds in the Sangre de Cristo Mountains of New Mexico. More than 75 percent of the strontium in the vegetation is ultimately derived from atmospheric transport and less than 25 percent from the weathering of the underlying rock. Much of the airborne strontium enters the watersheds by impacting on coniferous foliage, but deciduous foliage apparently traps little, if any, strontium-bearing aerosol. The strontium and presumably other nutrients are continuously recycled in a nearly closed system consisting of upper soil horizons, forest litter, and the standing crop of vegetation.

  14. The effect of carrier strontium on the absorption of oral doses of radioactive strontium in rats

    PubMed Central

    Harrison, G. E.; Jones, H. G.; Sutton, A.

    1957-01-01

    Carrier strontium had relatively little effect on the retention of an oral dose of radioactive strontium by the rat when it was administered immediately after the radioactive dose. The proportion of the radioactive dose which was excreted in the urine, on the other hand, increased progressively with the carrier dose. There was a decreased uptake of radioactive strontium in rats fed on a special low strontium diet. The effects of dietary strontium are discussed. Evidence was found of a discrimination by the rat against strontium in favour of calcium which was accounted for, at least in part, by a preferential urinary excretion of strontium. PMID:13460240

  15. Effects of oral supplementation with stable strontium

    PubMed Central

    Skoryna, Stanley C.

    1981-01-01

    The biologic effects of stable strontium, a naturally occurring trace element in the diet and the body, have been little investigated. This paper discusses the effects of oral supplementation with stable strontium in laboratory studies and clinical investigations. The extent of intestinal absorption of various doses of orally administered strontium was estimated by determining serum and tissue levels with atomic absorption spectrophotometry. The central observation is that increased oral intake produces a direct increase in serum levels and intracellular uptake of strontium. The results of these studies, as well as those of other investigators, demonstrate that a moderate dosage of stable strontium does not adversely affect the level of calcium either in the serum or in soft tissues. In studies of patients receiving 1 to 1.5 g/d of strontium gluconate, a sustained increase in the serum level of strontium produced a 100-fold increase in the strontium:calcium ratio. In rats, studies indicate that an increase in intracellular strontium content following supplementation may exert a protective effect on mitochondrial structure, probably by means of a stabilizing effect of strontium on membranes. The strontium:calcium ratio in animals receiving a standard diet is higher in the cell than in the extracellular fluid; this may be of physiologic significance. An increase in density that corresponded to the deposition of stable strontium was observed in areas of bone lesions due to metastatic cancer in patients receiving stable strontium supplementation. This suggests the possibility of using strontium to mineralize osteophenic areas and to relieve bone pain. Also, because of reports of an inverse relation between the incidence of dental caries and a high strontium content in drinking water, the use of natural water containing relatively high levels of stable strontium should be considered. In each of these instances it is important to maintain a normal dietary intake of

  16. Photostriction of strontium ruthenate

    PubMed Central

    Wei, Tzu-Chiao; Wang, Hsin-Ping; Liu, Heng-Jui; Tsai, Dung-Sheng; Ke, Jr-Jian; Wu, Chung-Lun; Yin, Yu-Peng; Zhan, Qian; Lin, Gong-Ru; Chu, Ying-Hao; He, Jr-Hau

    2017-01-01

    Transition metal oxides with a perovskite crystal structure exhibit a variety of physical properties associated with the lattice. Among these materials, strontium ruthenate (SrRuO3) displays unusually strong coupling of charge, spin and lattice degrees of freedom that can give rise to the photostriction, that is, changes in the dimensions of material due to the absorption of light. In this study, we observe a photon-induced strain as high as 1.12% in single domain SrRuO3, which we attribute to a nonequilibrium of phonons that are a result of the strong interaction between the crystalline lattice and electrons excited by light. In addition, these light-induced changes in the SrRuO3 lattice affect its electrical resistance. The observation of both photostriction and photoresistance in SrRuO3 suggests the possibility of utilizing the mechanical and optical functionalities of the material for next-generation optoelectronics, such as remote switches, light-controlled elastic micromotors, microactuators and other optomechanical systems. PMID:28436430

  17. Multiwavelength Strontium Vapor Lasers

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Yudin, N. A.

    2016-08-01

    Based on an analysis of experimental and theoretical works, modern notion on conditions of forming of population density inversion on self-terminating IR transitions of alkali-earth metals is given. It is demonstrated that there is a significant difference in the inversion formation in lasers on self-terminating transitions in the visible and near-IR ranges and lasers on self-terminating transitions of alkali-earth metals lasing IR lines in the mid-IR range. It is shown that in the discharge circuit of lasers on self-terminating metal atom transitions (LSMT) there are processes strengthening the influence of the known mechanism limiting the frequency and energy characteristics (FEC) of radiation caused by the presence of prepulse electron concentration. The mechanism of influence of these processes on FEC of the LSMT and technical methods of their neutralization are considered. The possibility of obtaining average lasing power of ~200 W from one liter volume of the active medium of the strontium vapor laser is demonstrated under conditions of neutralization of these processes.

  18. Degenerate Quantum Gases of Strontium

    NASA Astrophysics Data System (ADS)

    Stellmer, Simon; Schreck, Florian; Killian, Thomas C.

    2014-03-01

    Degenerate quantum gases of alkaline-earth-like elements open new opportunities in research areas ranging from molecular physics to the study of strongly correlated systems. These experiments exploit the rich electronic structure of these elements, which is markedly different from the one of other species for which quantum degeneracy has been attained. Specifically, alkaline-earth-like atoms, such as strontium, feature metastable triplet states, narrow intercombination lines, and a nonmagnetic, closed-shell ground state. This review covers the creation of quantum degenerate gases of strontium and the first experiments performed with this new system. It focuses on laser-cooling and evaporation schemes, which enable the creation of Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes, and shows how they are used for the investigation of optical Feshbach resonances, the study of degenerate gases loaded into an optical lattice, as well as the coherent creation of Sr2 molecules.

  19. The characteristic of strontium-site deficient perovskites SrxFe1.5Mo0.5O6-δ (x = 1.9-2.0) as intermediate-temperature solid oxide fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Yang, Guoquan; Feng, Jie; Sun, Wang; Dai, Ningning; Hou, Mingyue; Hao, Xiaoming; Qiao, Jinshuo; Sun, Kening

    2014-12-01

    As the cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), A-site deficient SrxFe1.5Mo0.5O6-δ (x = 1.9-2.0) (SxFM) materials have been successfully synthesized using the sol-gel combustion method. In the perovskite structure of these oxides, the unit cell varies from pseudocubic to cubic with increasing deficiency. Thermal expansion coefficient of SxFM has also been measured and compared with that of Scandium-stabilized zirconium (ScSZ) electrolyte. X-ray photoelectron spectroscopy (XPS) results indicate that the Sr-deficiency has changed the proportion of Fe2+/Fe3+ and Mo6+/Mo5+ ratios, which directly influences the conductivity of SxFM materials. S1.950FM possesses the largest electrical conductivity and the lowest polarization resistance (Rp) among all the samples. The maximum power densities of a single cell with the S1.950FM cathode reaches 1083 mW cm-2, and the area specific resistance value is 0.17 Ω cm2 at 800 °C. These results indicate that the A-site deficiency could promote the electrochemical performance of SFM materials as cathodes for IT-SOFCs.

  20. Exploring strontium titanate as a reforming catalyst for dodecane

    NASA Astrophysics Data System (ADS)

    Hbaieb, K.

    2016-08-01

    Yttrium-doped strontium titanate (YST)-based perovskite has been explored as catalyst for reforming dodecane. Active metal elements such as ruthenium, nickel and cobalt were doped on the B-site of the perovskite to boost the catalyst activity. Commercial Ni-alumina catalyst has been used for benchmarking. Both steam and autothermal reforming schemes have been used at 800 and 850 °C. Irrespective of the doping elements, all catalysts performed well and had comparable activity and conversion as the commercial catalyst with slight advantage for ruthenium followed by nickel-based catalysts. Hydrogen and syngas yields fall into the range of 65-75 and 83-91 %, respectively. Conversion was consistently between 84 and 90 %. As such, the YST-based perovskite is a promising catalyst for reforming of heavy liquid hydrocarbon fuel.

  1. Development of Technologies for the Simultaneous Separation of Cesium and Strontium from Spent Nuclear Fuel as Part of an Advanced Fuel Cycle

    SciTech Connect

    Jack D. Law; R. Scott HErbst; David H. Meikrantz; Dean R. Peterman; Catherine L. Riddle; Richard D. Tillotson; Terry A. Todd

    2005-04-01

    As part of the Advanced Fuel Cycle Initiative, two solvent extraction technologies are being developed to simultaneously separate cesium and strontium from dissolved spent nuclear fuel. The first process utilizes a solvent consisting of chlorinated cobalt dicarbollide and polyethylene glycol extractants in a phenyltrifluoromethyl sulfone diluent. Recent improvements to the process include development of a new, non-nitroaromatic diluent and development of new stripping reagents, including a regenerable strip reagent that can be recovered and recycled. Countercurrent flowsheets have been designed and tested on simulated and actual spent nuclear fuel feed streams with both cesium and strontium removal efficiencies of greater than 99 %. The second process developed to simultaneously separate cesium and strontium from spent nuclear fuel is based on two highly-specific extractants: 4,4',(5')-Di-(t-butyldicyclo-hexano)-18-crown-6 (DtBuCH18C6) and Calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6). The DtBuCH18C6 extractant is selective for strontium and the BOBCalixC6 extractant is selective for cesium. A solvent composition has been developed that enables both elements to be removed together and, in fact, a synergistic effect was observed with strontium distributions in the combined solvent that are much higher that in the strontium extraction (SREX) process. Initial laboratory test results of the new combined cesium and strontium extraction process indicate good extraction and stripping performance. A flowsheet for treatment of spent nuclear fuel is currently being developed.

  2. Strontium substitution for calcium in lithogenesis.

    PubMed

    Blaschko, Sarah D; Chi, Thomas; Miller, Joe; Flechner, Lawrence; Fakra, Sirine; Kapahi, Pankaj; Kahn, Arnold; Stoller, Marshall L

    2013-02-01

    Strontium has chemical similarity to calcium, which enables the replacement of calcium by strontium in biomineralization processes. Incorporating strontium into human bone and teeth has been studied extensively but little research has been performed of the incorporation of strontium into urinary calculi. We used synchrotron based x-ray fluorescence and x-ray absorption techniques to examine the presence of strontium in different types of human kidney stones. Multiple unique human stone samples were obtained via consecutive percutaneous nephrolithotomies/ureteroscopies. A portion of each stone was sent for standard laboratory analysis and a portion was retained for x-ray fluorescence and x-ray absorption measurements. X-ray fluorescence and x-ray absorption measurements determined the presence, spatial distribution and speciation of strontium in each stone sample. Traditional kidney stone analyses identified calcium oxalate, calcium phosphate, uric acid and cystine stones. X-ray fluorescence measurements identified strontium in all stone types except pure cystine. X-ray fluorescence elemental mapping of the samples revealed co-localization of calcium and strontium. X-ray absorption measurements of the calcium phosphate stone showed strontium predominately present as strontium apatite. Advanced x-ray fluorescence imaging identified strontium in all calcium based stones, present as strontium apatite. This finding may be critical since apatite is thought to be the initial nidus for calcium stone formation. Strontium is not identified by standard laboratory stone analyses. Its substitution for calcium can be reliably identified in stones from multiple calcium based stone formers, which may offer opportunities to gain insight into early events in lithogenesis. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  3. Strontium: Part II. Chemistry, Biological Aspects and Applications.

    ERIC Educational Resources Information Center

    Britton, G. C.; Johnson, C. H.

    1987-01-01

    Reviews basic information on the Chemistry of strontium and its compounds. Explains biological aspects of strontium and its pharmaceutical applications. Highlights industrial application of strontium and its components. (ML)

  4. Strontium is incorporated in different levels into bones and teeth of rats treated with strontium ranelate.

    PubMed

    Oliveira, Josianne P; Querido, William; Caldas, Rogério J; Campos, Andrea P C; Abraçado, Leida G; Farina, Marcos

    2012-09-01

    The aim of this study was to evaluate the strontium incorporation into specific bones and teeth of rats treated with strontium ranelate. The relative strontium levels [Sr/(Ca + Sr) ratio] were obtained by synchrotron radiation micro X-ray fluorescence. The incisor teeth were further examined by energy dispersive X-ray spectroscopy (EDS) in a scanning electron microscope. The isolated mineral phase was investigated by EDS in a transmission electron microscope and X-ray diffraction. The strontium content was markedly increased in animals treated with strontium ranelate, with different incorporation levels found among specific bones, regions within the same bone and teeth. The highest strontium levels were observed in the iliac crest, mandible and calvaria, while the lowest were observed in the femoral diaphysis, lumbar vertebrae, rib and alveolar bone. The strontium content was higher in the femoral neck than in the diaphysis. The strontium levels also varied within the alveolar bone. High levels of strontium were found in the incisor tooth, with values similar to those in the iliac crest. Strontium was observed in both enamel and dentin. The strontium content of the molar tooth was negligible. Strontium was incorporated into the mineral substance, with up to one strontium replacing one out of 10 calcium ions within the apatite crystal lattice. The mineral from treated animals presented increased lattice parameters, which might be associated to their bone strontium contents. In conclusion, the incorporation of strontium occurred in different levels into distinct bones, regions within the same bone and teeth of rats treated with strontium ranelate.

  5. Cobalt metabolism and toxicology--a brief update.

    PubMed

    Simonsen, Lars Ole; Harbak, Henrik; Bennekou, Poul

    2012-08-15

    Cobalt metabolism and toxicology are summarized. The biological functions of cobalt are updated in the light of recent understanding of cobalt interference with the sensing in almost all animal cells of oxygen deficiency (hypoxia). Cobalt (Co(2+)) stabilizes the transcriptional activator hypoxia-inducible factor (HIF) and thus mimics hypoxia and stimulates erythropoietin (Epo) production, but probably also by the same mechanism induces a coordinated up-regulation of a number of adaptive responses to hypoxia, many with potential carcinogenic effects. This means on the other hand that cobalt (Co(2+)) also may have beneficial effects under conditions of tissue hypoxia, and possibly can represent an alternative to hypoxic preconditioning. Cobalt is acutely toxic in larger doses, and in mammalian in vitro test systems cobalt ions and cobalt metal are cytotoxic and induce apoptosis and at higher concentrations necrosis with inflammatory response. Cobalt metal and salts are also genotoxic, mainly caused by oxidative DNA damage by reactive oxygen species, perhaps combined with inhibition of DNA repair. Of note, the evidence for carcinogenicity of cobalt metal and cobalt sulfate is considered sufficient in experimental animals, but is as yet considered inadequate in humans. Interestingly, some of the toxic effects of cobalt (Co(2+)) have recently been proposed to be due to putative inhibition of Ca(2+) entry and Ca(2+)-signaling and competition with Ca(2+) for intracellular Ca(2+)-binding proteins. The tissue partitioning of cobalt (Co(2+)) and its time-dependence after administration of a single dose have been studied in man, but mainly in laboratory animals. Cobalt is accumulated primarily in liver, kidney, pancreas, and heart, with the relative content in skeleton and skeletal muscle increasing with time after cobalt administration. In man the renal excretion is initially rapid but decreasing over the first days, followed by a second, slow phase lasting several weeks

  6. Strontium Content and Variable Strontium-Chlorinity Relationship of Sargasso Sea Water.

    PubMed

    Mackenzie, F T

    1964-10-23

    Sargasso Sea water has a variable strontium-chlorinity relationship. This observation is contrary to the view that strontium in the ocean is in constant proportion to chlorinity. It is suggested that the increase in strontium concentration at 500 to 800 meters in Sargasso Sea water results from interaction between organic aggregates and the water.

  7. PREPARATION OF TE SYNTHETIC STRONTIUM ISOMORPH OF COLEMANITE AND OTHER RELATED STRONTIUM BORATE HYDRATES,

    DTIC Science & Technology

    strontium iodate, (2) miscellaneous conversion reactions in borax and boric acid solution, (3) reactions of ammonium pentaborate and strontium...This compound is the strontium isomorph of cole manite (2CaO.3B2O3.5H2O). The following series of reactions were investigated: (1) reactions of borax and

  8. Combined transuranic-strontium extraction process

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    The transuranic (TRU) elements neptunium, plutonium and americium can be separated together with strontium from nitric acid waste solutions in a single process. An extractant solution of a crown ether and an alkyl(phenyl)-N,N-dialkylcarbanylmethylphosphine oxide in an appropriate diluent will extract the TRU's together with strontium, uranium and technetium. The TRU's and the strontium can then be selectively stripped from the extractant for disposal.

  9. Combined transuranic-strontium extraction process

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1992-12-08

    The transuranic (TRU) elements neptunium, plutonium and americium can be separated together with strontium from nitric acid waste solutions in a single process. An extractant solution of a crown ether and an alkyl(phenyl)-N,N-dialkylcarbanylmethylphosphine oxide in an appropriate diluent will extract the TRU's together with strontium, uranium and technetium. The TRU's and the strontium can then be selectively stripped from the extractant for disposal. 3 figs.

  10. Combined transuranic-strontium extraction process

    SciTech Connect

    Horwitz, E.P.; Dietz, M.L.

    1991-12-31

    The transuranic (TRU) elements neptunium, plutonium and amercium can be separated together with strontium from nitric acid waste solutions in a single process. An extractant solution of a crown ether and an alkyl(phenyl)-N.N-dialkylcarbanylmethylphosphine oxide in an appropriate diluent will extract the TRU`s to gather with strontium, uranium and technetium. The TRU`s and the strontium can then be selectively stripped from the extractant for disposal.

  11. Cobalamin deficiency.

    PubMed

    Herrmann, Wolfgang; Obeid, Rima

    2012-01-01

    Cobalamin (Cbl, vitamin B12) consists of a corrinoid structure with cobalt in the centre of the molecule. Neither humans nor animals are able to synthesize this vitamin. Foods of animal source are the only natural source of cobalamin in human diet. There are only two enzymatic reactions in mammalian cells that require cobalamin as cofactor. Methylcobolamin is a cofactor for methionine synthase. The enzyme methylmalonyl-CoA-mutase requires adenosylcobalamin as a cofactor. Therefore, serum concentrations of homocysteine (tHcy) and methylmalonic acid (MMA) will increase in cobalamin deficiency. The cobalamin absorption from diet is a complex process that involves different proteins: haptocorrin, intrinsic factor and transcobalamin (TC). Cobalamin that is bound to TC is called holotranscobalamin (holoTC) which is the metabolically active vitamin B12 fraction. HoloTC consists 6 and 20% of total cobalamin whereas 80% of total serum cobalamin is bound to another binding protein, haptocorrin. Cobalamin deficiency is common worldwide. Cobalamin malabsorption is common in elderly subjects which might explain low vitamin status. Subjects who ingest low amount of cobalamin like vegetarians develop vitamin deficiency. No single parameter can be used to diagnose cobalamin deficiency. Total serum cobalamin is neither sensitive nor it is specific for cobalamin deficiency. This might explain why many deficient subjects would be overlooked by utilizing total cobalamin as status marker. Concentration of holotranscobalamin (holoTC) in serum is an earlier marker that becomes decreased before total serum cobalamin. Concentrations of MMA and tHcy increase in blood of cobalamin deficient subjects. Despite limitations of these markers in patients with renal dysfunction, concentrations of MMA and tHcy are useful functional markers of cobalamin status. The combined use of holoTC and MMA assays may better indicate cobalamin status than either of them. Because Cbl deficiency is a risk factor

  12. Separation of strontium from fecal matter

    DOEpatents

    Kester, Dianne K.

    1995-01-01

    A method of separating strontium from a sample of biomass potentially contaminated with various radionuclides. After the sample is reduced, dissociated, and carried on a first precipitate of actinides, the first precipitate is removed to leave a supernate. Next, oxalic acid is added to the supernate to cause a second precipitate of strontium and calcium. Then, after separating the second precipitate, nitric acid is added to the second precipitate to cause a third precipitate of strontium. The calcium remains in solution and is discarded to leave essentially the precipitate of strontium.

  13. Separation of strontium from fecal matter

    DOEpatents

    Kester, D.K.

    1995-01-03

    A method is presented of separating strontium from a sample of biomass potentially contaminated with various radionuclides. After the sample is reduced, dissociated, and carried on a first precipitate of actinides, the first precipitate is removed to leave a supernate. Next, oxalic acid is added to the supernate to cause a second precipitate of strontium and calcium. Then, after separating the second precipitate, nitric acid is added to the second precipitate to cause a third precipitate of strontium. The calcium remains in solution and is discarded to leave essentially the precipitate of strontium.

  14. METHOD OF REMOVING STRONTIUM IONS

    DOEpatents

    Rhodes, D.W.; McHenry, J.R.; Ames, L.L. Jr.

    1962-05-01

    A method is given for removing trace amounts of Sr/sup 90/ from solutions. Phosphate ion is added to the solution and it is then brought into contact with a solid salt such as calcium carbonate which will react methathetically with the phosphate ion to form a salt such as calcium phosphate. During this reaction, strontium will be absorbed to a high degree within the newly formed lattice. (AEC)

  15. Marine cobalt resources

    USGS Publications Warehouse

    Manheim, F. T.

    1986-01-01

    Ferromanganese oxides in the open oceans are more enriched in cobalt than any other widely distributed sediments or rocks. Concentrations of cobalt exceed 1 percent in ferromanganese crusts on seamounts, ocean ridges, and other raised areas of the ocean. The cobalt-rich crusts may be the slowest growing of any earth material, accumulating one molecular layer every 1 to 3 months. Attention has been drawn to crusts as potential resources because they contain cobalt, manganese, and platinum, three of the four priority strategic metals for the United States. Moreover, unlike abyssal nodules, whose recovery is complicated by their dominant location in international waters, some of the most cobalt-rich crusts occur within the exclusive economic zone of the United States and other nations. Environmental impact statements for crust exploitation are under current development by the Department of the Interior.

  16. Assessment of strontium oxide functionalized graphene nanoflakes for enhanced photocatalytic activity: A density functional theory approach

    SciTech Connect

    Divya, A.; Mathavan, T. Asath, R. Mohamed; Benial, A. Milton Franklin; Archana, J.; Hayakawa, Y.

    2016-05-23

    A series of strontium oxide functionalized graphene nanoflakes were designed and their optoelectronic properties were studied for enhanced photocatalytic activity. The efficiency of designed molecules was studied using various parameters such as HOMO-LUMO energy gap, light harvesting efficiency and exciton binding energy. The computed results show that by increasing the degree of functionalization of strontium oxide leads to lowering the band gap of hydrogen terminated graphene nanoflakes. Furthermore, the study explores the role of strontium oxide functionalization in Frontier Molecular Orbitals, ionization potential, electron affinity, exciton binding energy and light harvesting efficiency of designed molecules. The infrared and Raman spectra were simulated for pure and SrO functionalized graphene nanoflakes. The electron rich and electron deficient regions which are favorable for electrophilic and nucleophilic attacks respectively were analyzed using molecular electrostatic potential surface analysis.

  17. Assessment of strontium oxide functionalized graphene nanoflakes for enhanced photocatalytic activity: A density functional theory approach

    NASA Astrophysics Data System (ADS)

    Divya, A.; Mathavan, T.; Asath, R. Mohamed; Archana, J.; Hayakawa, Y.; Benial, A. Milton Franklin

    2016-05-01

    A series of strontium oxide functionalized graphene nanoflakes were designed and their optoelectronic properties were studied for enhanced photocatalytic activity. The efficiency of designed molecules was studied using various parameters such as HOMO-LUMO energy gap, light harvesting efficiency and exciton binding energy. The computed results show that by increasing the degree of functionalization of strontium oxide leads to lowering the band gap of hydrogen terminated graphene nanoflakes. Furthermore, the study explores the role of strontium oxide functionalization in Frontier Molecular Orbitals, ionization potential, electron affinity, exciton binding energy and light harvesting efficiency of designed molecules. The infrared and Raman spectra were simulated for pure and SrO functionalized graphene nanoflakes. The electron rich and electron deficient regions which are favorable for electrophilic and nucleophilic attacks respectively were analyzed using molecular electrostatic potential surface analysis.

  18. Strontium mineralization of shark vertebrae

    PubMed Central

    Raoult, Vincent; Peddemors, Victor M.; Zahra, David; Howell, Nicholas; Howard, Daryl L.; de Jonge, Martin D.; Williamson, Jane E.

    2016-01-01

    Determining the age of sharks using vertebral banding is a vital component of management, but the causes of banding are not fully understood. Traditional shark ageing is based on fish otolith ageing methods where growth bands are assumed to result from varied seasonal calcification rates. Here we investigate these assumptions by mapping elemental distribution within the growth bands of vertebrae from six species of sharks representing four different taxonomic orders using scanning x-ray fluorescence microscopy. Traditional visual growth bands, determined with light microscopy, were more closely correlated to strontium than calcium in all species tested. Elemental distributions suggest that vertebral strontium bands may be related to environmental variations in salinity. These results highlight the requirement for a better understanding of shark movements, and their influence on vertebral development, if confidence in age estimates is to be improved. Analysis of shark vertebrae using similar strontium-focused elemental techniques, once validated for a given species, may allow more successful estimations of age on individuals with few or no visible vertebral bands. PMID:27424768

  19. Strontium mineralization of shark vertebrae.

    PubMed

    Raoult, Vincent; Peddemors, Victor M; Zahra, David; Howell, Nicholas; Howard, Daryl L; de Jonge, Martin D; Williamson, Jane E

    2016-07-18

    Determining the age of sharks using vertebral banding is a vital component of management, but the causes of banding are not fully understood. Traditional shark ageing is based on fish otolith ageing methods where growth bands are assumed to result from varied seasonal calcification rates. Here we investigate these assumptions by mapping elemental distribution within the growth bands of vertebrae from six species of sharks representing four different taxonomic orders using scanning x-ray fluorescence microscopy. Traditional visual growth bands, determined with light microscopy, were more closely correlated to strontium than calcium in all species tested. Elemental distributions suggest that vertebral strontium bands may be related to environmental variations in salinity. These results highlight the requirement for a better understanding of shark movements, and their influence on vertebral development, if confidence in age estimates is to be improved. Analysis of shark vertebrae using similar strontium-focused elemental techniques, once validated for a given species, may allow more successful estimations of age on individuals with few or no visible vertebral bands.

  20. Simulating the Transfer of Strontium-90 from Soil to Leafy Vegetables by Using Strontium-88.

    PubMed

    Kuke, Ding; Shujuan, Liu; Yingxue, He; Dong, Yan; Fengshou, Zhang; Shuifeng, Wang; Jinghua, Guo; Wei, Zhang; Xin, Wang; Xiaoyan, Jiang

    2016-01-01

    The transfer, from soil to Chinese cabbage and spinach, of radioactive strontium-90 released as a result of accidents in nuclear power stations was studied using a stable isotope of strontium, namely nuclide strontium-88 ((88)Sr). The study led to an experimental model for assessing the hazard of radionuclide strontium-90 ((90)Sr) entering the food chain and for predicting the risk to food safety. Chinese cabbage and spinach were grown in pots in a greenhouse and irrigated with deionized water containing known quantities of strontium. Based on the strontium content of that water, the plants were divided into five groups (treatments) and strontium content of the soil, and 30-day-old plants were determined by inductively coupled plasma atomic emission spectroscopy instrument (ICP-AES). Data on the strontium content of soil and plants enabled the development of a model using MATLAB, a mathematical software package, which included curve fitting and problem solving using regression equations and differential equations. Although strontium curves for leaves, stems, and roots of Chinese cabbage were not exactly the same, all showed a non-linear increase when compared with the increase in the content of strontium in soil. Strontium curves for leaves, stems, and roots of spinach were very similar and showed an initial increase followed by a decrease. Strontium concentrations in both Chinese cabbage and spinach were initially related to the concentrations of sodium and sulfur, the next two relevant nuclides being calcium and magnesium. The relationship between calcium and strontium in Chinese cabbage was different from that in spinach. By using (88)Sr to simulate the transfer of radionuclide (90)Sr from soil to a crop, the relevant data required to deal with accidental release of strontium can be obtained using a fitting curve and regression equations, thereby providing some experimental basis for evaluating the potential hazards posed by such accidents to the food chain.

  1. Magnetism in cobalt clusters

    NASA Astrophysics Data System (ADS)

    Emmert, Jeffrey Wayne

    The results of Stern-Gerlach type magnetic deflection experiments on clusters of cobalt consisting of 15 to 200 atoms are reported. These cobalt clusters exhibit superparamagnetic behavior over a wide range of temperatures and applied magnetic fields. The average magnetic moment per atom was determined for each cluster size. These range from 2.28 muB to 3.40 mu B, significantly exceeding the 1.72 muB per atom moment of bulk cobalt. This enhanced magnetism predictably decreases with increasing cluster size, but the evolution to the bulk is not smooth and exhibits detailed structure.

  2. Alterations of histone modifications by cobalt compounds

    PubMed Central

    Li, Qin; Ke, Qingdong; Costa, Max

    2009-01-01

    In the present study, we examined the effects of CoCl2 on multiple histone modifications at the global level. We found that in both human lung carcinoma A549 cells and human bronchial epithelial Beas-2B cells, exposure to CoCl2 (≥200 μM) for 24 h increased H3K4me3, H3K9me2, H3K9me3, H3K27me3, H3K36me3, uH2A and uH2B but decreased acetylation at histone H4 (AcH4). Further investigation demonstrated that in A549 cells, the increase in H3K4me3 and H3K27me3 by cobalt ions exposure was probably through enhancing histone methylation processes, as methionine-deficient medium blocked the induction of H3K4me3 and H3K27me3 by cobalt ions, whereas cobalt ions increased H3K9me3 and H3K36me3 by directly inhibiting JMJD2A demethylase activity in vitro, which was probably due to the competition of cobalt ions with iron for binding to the active site of JMJD2A. Furthermore, in vitro ubiquitination and deubiquitination assays revealed that the cobalt-induced histone H2A and H2B ubiquitination is the result of inhibition of deubiquitinating enzyme activity. Microarray data showed that exposed to 200 μM of CoCl2 for 24 h, A549 cells not only increased but also decreased expression of hundreds of genes involved in different cellular functions, including tumorigenesis. This study is the first to demonstrate that cobalt ions altered epigenetic homeostasis in cells. It also sheds light on the possible mechanisms involved in cobalt-induced alteration of histone modifications, which may lead to altered programs of gene expression and carcinogenesis since cobalt at higher concentrations is a known carcinogen. PMID:19376846

  3. Imbalance in the oceanic strontium budget

    NASA Astrophysics Data System (ADS)

    Davis, Amy C.; Bickle, Mike J.; Teagle, Damon A. H.

    2003-06-01

    Palmer and Edmond [Earth Planet. Sci. Lett. 92 (1989) 11-26] indicated that thermally plausible oceanic hydrothermal inputs of strontium to the oceans are not sufficient to balance the riverine input. It has recently been suggested that off-axis low-temperature hydrothermal circulation may reconcile this discrepancy [e.g. Butterfield et al., Geochim. Cosmochim. Acta 65 (2001) 4141-4153]. Strontium isotope alteration profiles are compiled for sampled in situ ocean and ophiolite crust to calculate a sustainable cumulative hydrothermal flux to the oceanic strontium budget. High-temperature circulation contributes ˜1.8×10 9 mol yr -1 of basaltic strontium to the oceans. Enhanced hydrothermal systems in arc-related spreading environments (10% of the crust) may increase this to ˜2.3×10 9 mol yr -1. It is shown that low-temperature flow cannot supply the remaining flux required to reconcile the oceanic strontium budget (˜8.7×10 9 mol yr -1) because this would require 100% exchange of seawater strontium for basaltic strontium over an 820 m section of MORB-like crust. Currently sampled in situ ocean crust is not altered to this extent. The isotopic alteration intensity of 120 Myr crust sampled in DSDP Holes 417D and 418A indicates that off-axis low-temperature flow may contribute up to ˜8×10 8 mol yr -1 of basaltic strontium (9% of that required). The ocean crust can sustain a total basaltic strontium flux of ˜3.1±0.8×10 9 mol yr -1 ( 87Sr/ 86Sr ˜0.7025) to the oceans. This is consistent with hydrothermal flux estimates, but remains less than a third of the flux required to balance the oceanic strontium budget. The ocean crust cannot support a higher hydrothermal contribution unless the average ocean crust is significantly more altered than current observation.

  4. Samarium/Cobalt Magnets

    NASA Technical Reports Server (NTRS)

    Das, D.; Kumar, K.; Frost, R.; Chang, C.

    1985-01-01

    Intrinsic magnetic coercivities of samarium cobalt magnets made to approach theoretical limit of 350 kA/m by carefully eliminating oxygen from finished magnet by hot isostatic pressing (HIP). HIP process viable alternative to currently used sintering process.

  5. Samarium/Cobalt Magnets

    NASA Technical Reports Server (NTRS)

    Das, D.; Kumar, K.; Frost, R.; Chang, C.

    1985-01-01

    Intrinsic magnetic coercivities of samarium cobalt magnets made to approach theoretical limit of 350 kA/m by carefully eliminating oxygen from finished magnet by hot isostatic pressing (HIP). HIP process viable alternative to currently used sintering process.

  6. Quantum Degenerate Gases of Strontium

    NASA Astrophysics Data System (ADS)

    Desalvo, Brian; Martinez de Escobar, Natali; Mickelson, Pacal; Yan, Mi; Killian, Thomas

    2010-03-01

    We have produced quantum degenerate gases of three of the four stable isotopes of strontium. Using two-stage laser trapping and cooling followed by direct evaporative cooling in a far-off- resonance optical dipole trap (ODT), a stable Bose-Einstein Condensate (BEC) of ^84Sr is formed. Via dual species trapping and sympathetic cooling in an ODT, an attractive BEC of ^88Sr is created, as well as a degenerate Fermi gas of ^87Sr. Differences in the evaporation scheme used to reach degeneracy for each isotope will be presented as well as the varied dynamics of the gases.

  7. Effect of ‘A’-site non stoichiometry in strontium doped lanthanum ferrite based solid oxide fuel cell cathodes

    SciTech Connect

    Banerjee, Koyel; Mukhopadhyay, Jayanta Barman, Madhurima; Basu, Rajendra N.

    2015-12-15

    Highlights: • La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2 system varying La-site (0.6–0.54) are studied. • Combustion synthesis technique is used to prepare the powder samples. • Highest electrical conductivity observed with largest A-site deficit composition. • Lowest cathode polarization is found with the same composition (0.02 Ω cm{sup 2}). • Composition with largest A-site deficiency exhibits best performance (2.84 A cm{sup −2}). - Abstract: Effect of A-site non-stoichiometry in strontium doped lanthanum cobalt ferrite (La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2) is studied in a systematic manner with variation of ‘A’ site stoichiometry from 1 to 0.94. The perovskite based cathode compositions are synthesized by combustion synthesis. Powder characterizations reveal rhombohedral crystal structure with crystallite size ranging from 29 to 34 nm with minimum lattice spacing of 0.271 nm. Detailed sintering studies along with total DC electrical conductivities are evaluated in the bulk form with variation of sintering temperatures. The electrode polarizations are measured in the symmetric cell configuration by impedance spectroscopy which is found to be the lowest (0.02 Ω cm{sup 2} at 800 °C) for cathode having highest degree of ‘A’-site deficiency. The same cathode composition exhibits a current density of 2.84 A cm{sup −2} (at 0.7 V, 800 °C) in anode-supported single cell. An attempt has been made to correlate the trend of electrical behaviour with increasing ‘A’-site deficiency for such cathode compositions.

  8. Solvothermal synthesis of strontium phosphate chloride nanowire

    NASA Astrophysics Data System (ADS)

    Lam, W. M.; Wong, C. T.; Li, Z. Y.; Luk, K. D. K.; Chan, W. K.; Yang, C.; Chiu, K. Y.; Xu, B.; Lu, W. W.

    2007-08-01

    Strontium phosphate chloride nanowire was synthesized via a solvothermal treatment of strontium tri-polyphosphate and Collin salt in 1,4-dioxane at 150 °C. The effects of 1,4-dioxane concentration on particle morphology, crystallinity and phase purity were investigated in this study. The specimen morphology was analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). When the concentration of 1,4-dioxane was below 10%, micron-sized whisker was the dominant form. At 20-25% concentration of 1,4-dioxane, strontium phosphate chloride single-crystalline nanowire was 31±12 nm in diameter and 1.43±0.6 μm in length with an aspect ratio of 52.28±29.41. X-ray diffraction (XRD) pattern of this nanowire matched with that of strontium phosphate chloride (JCPDS #083-0973). When 1,4-dioxane concentration exceeded 25%, nanorod aggregate was the dominant form instead of nanowire. At 20-25% 1,4-dioxane concentration suitable strontium concentration combine with high chemical potential environment favors the formation of nanowires. By adding 1,4-dioxane impure phase such as β-strontium hydrogen phosphate, nanorod formation was suppressed. This method provides an efficient way to synthesize high aspect ratio strontium phosphate chloride nanowire. It has potential bioactive nanocomposite, high mechanical performance bioactive bone cement filler and fluorescent material applications.

  9. Thermoelectric Power Generation from Lanthanum Strontium Titanium Oxide at Room Temperature through the Addition of Graphene.

    PubMed

    Lin, Yue; Norman, Colin; Srivastava, Deepanshu; Azough, Feridoon; Wang, Li; Robbins, Mark; Simpson, Kevin; Freer, Robert; Kinloch, Ian A

    2015-07-29

    The applications of strontium titanium oxide based thermoelectric materials are currently limited by their high operating temperatures of >700 °C. Herein, we show that the thermal operating window of lanthanum strontium titanium oxide (LSTO) can be reduced to room temperature by the addition of a small amount of graphene. This increase in operating performance will enable future applications such as generators in vehicles and other sectors. The LSTO composites incorporated one percent or less of graphene and were sintered under an argon/hydrogen atmosphere. The resultant materials were reduced and possessed a multiphase structure with nanosized grains. The thermal conductivity of the nanocomposites decreased upon the addition of graphene, whereas the electrical conductivity and power factor both increased significantly. These factors, together with a moderate Seebeck coefficient, meant that a high power factor of ∼2500 μWm(-1)K(-2) was reached at room temperature at a loading of 0.6 wt % graphene. The highest thermoelectric figure of merit (ZT) was achieved when 0.6 wt % graphene was added (ZT = 0.42 at room temperature and 0.36 at 750 °C), with >280% enhancement compared to that of pure LSTO. A preliminary 7-couple device was produced using bismuth strontium cobalt oxide/graphene-LSTO pucks. This device had a Seebeck coefficient of ∼1500 μV/K and an open voltage of 600 mV at a mean temperature of 219 °C.

  10. Factors affecting strontium absorption in drownings.

    PubMed

    Azparren, J E; Perucha, E; Martínez, P; Muñoz, R; Vallejo, G

    2007-05-24

    This study examines the effects of age, gender, a cold water medium versus warm water medium, and salinity on strontium levels determined in left ventricular blood in drownings. Significant differences in the amount of strontium absorbed into the bloodstream (p<0.001) were detected between individuals who drowned in fresh water versus those drowning in seawater, and between those drowning in cold water versus warm water (p=0.030). However, no significant differences were noted in the strontium concentrations of left ventricular blood according to gender or age.

  11. Mercury-based cobalt magnetic fluids and cobalt nanoparticles

    NASA Astrophysics Data System (ADS)

    Massart, R.; Rasolonjatovo, B.; Neveu, S.; Cabuil, V.

    2007-01-01

    This paper describes the synthesis of a magnetic and conducting liquid consisting of cobalt nanoparticles dispersed in mercury. The magnetic nanoparticles are obtained in one step by the electroreduction of a cobalt(II) solution on mercury. These particles are then extracted using an organic solution of surfactant in order to obtain a ferrofluid based on cobalt nanoparticles.

  12. Catalysis: Cobalt gets in shape

    NASA Astrophysics Data System (ADS)

    Claeys, Michael

    2016-10-01

    Solid cobalt-based catalysts are used commercially to convert carbon monoxide and hydrogen into synthetic fuels. It emerges that much more valuable chemicals can be produced by using a different form of cobalt catalyst. See Letter p.84

  13. Trapping and evaporation of strontium-87 and strontium-88 mixtures

    NASA Astrophysics Data System (ADS)

    Mickelson, Pascal Gerry

    This thesis describes trapping and evaporative cooling of ultracold 87Sr and 88Sr mixtures in an optical dipole trap to produce the first Bose-Einstein condensate (BEC) of 88Sr. Furthermore, this work presents thermalization studies that characterize the scattering properties of these ultracold strontium samples. Such ultracold atomic gases have become an important area of research because of their potential for improving optical frequency standards and for realizing quantum computation using neutral atoms. A BEC of 88Sr is particularly interesting because the small value of its background s-wave scattering length may enable the use of optical Feshbach resonances to create two-dimensional solitons. However, the small scattering length for 88Sr also hinders efficient evaporative cooling in the optical dipole trap, a necessary step to producing a BEC. Experiments with other ultracold gases have successfully overcome this hurdle by mixing in a second atomic species which, by introducing stronger interactions with the weakly interacting species, enables evaporation to colder temperatures via sympathetic cooling. For this work, we use 87Sr to sympathetically cool 88Sr during forced evaporation to quantum degeneracy. Previous experiments in the Killian Lab characterized 88Sr in detail. Here, I emphasize the new or improved aspects that have allowed trapping and cooling of the mixtures of 87Sr and 88 Sr: trapping of 87Sr by itself, spectroscopic measurements of all the stable strontium isotopes to guide the trapping of isotopic mixtures, imaging of both 87Sr and 88Sr, and the various trade-offs necessary to simultaneously trap 87Sr and 88Sr. Finally, I discuss how the thermalization studies of the scattering properties of the isotopes guide the forced evaporation of mixed isotope samples. These efforts result in the production of the BEC of 88Sr, but they also point the way to future studies of fermionic quantum degeneracy in 87Sr and to the rich physics of mixed species

  14. Cobalt catalysis involving π components in organic synthesis.

    PubMed

    Gandeepan, Parthasarathy; Cheng, Chien-Hong

    2015-04-21

    Over the last three decades, transition-metal-catalyzed organic transformations have been shown to be extremely important in organic synthesis. However, most of the successful reactions are associated with noble metals, which are generally toxic, expensive, and less abundant. Therefore, we have focused on catalysis using the abundant first-row transition metals, specifically cobalt. In this Account, we demonstrate the potential of cobalt catalysis in organic synthesis as revealed by our research. We have developed many useful catalytic systems using cobalt complexes. Overall, they can be classified into several broad types of reactions, specifically [2 + 2 + 2] and [2 + 2] cycloadditions; enyne reductive coupling; reductive [3 + 2] cycloaddition of alkynes/allenes with enones; reductive coupling of alkyl iodides with alkenes; addition of organoboronic acids to alkynes, alkenes, or aldehydes; carbocyclization of o-iodoaryl ketones/aldehydes with alkynes/electron-deficient alkenes; coupling of thiols with aryl and alkyl halides; enyne coupling; and C-H bond activation. Reactions relying on π components, specifically cycloaddition, reductive coupling, and enyne coupling, mostly afford products with excellent stereo- and regioselectivity and superior atom economy. We believe that these cobalt-catalyzed π-component coupling reactions proceed through five-membered cobaltacyclic intermediates formed by the oxidative cyclometalation of two coordinated π bonds of the substrates to the low-valent cobalt species. The high regio- and stereoselectivity of these reactions are achieved as a result of the electronic and steric effects of the π components. Mostly, electron-withdrawing groups and bulkier groups attached to the π bonds prefer to be placed near the cobalt center of the cobaltacycle. Most of these transformations proceed through low-valent cobalt complexes, which are conveniently generated in situ from air-stable Co(II) salts by Zn- or Mn-mediated reduction

  15. The Ferroportin Metal Efflux Proteins Function in Iron and Cobalt Homeostasis in Arabidopsis[W][OA

    PubMed Central

    Morrissey, Joe; Baxter, Ivan R.; Lee, Joohyun; Li, Liangtao; Lahner, Brett; Grotz, Natasha; Kaplan, Jerry; Salt, David E.; Guerinot, Mary Lou

    2009-01-01

    Relatively little is known about how metals such as iron are effluxed from cells, a necessary step for transport from the root to the shoot. Ferroportin (FPN) is the sole iron efflux transporter identified to date in animals, and there are two closely related orthologs in Arabidopsis thaliana, IRON REGULATED1 (IREG1/FPN1) and IREG2/FPN2. FPN1 localizes to the plasma membrane and is expressed in the stele, suggesting a role in vascular loading; FPN2 localizes to the vacuole and is expressed in the two outermost layers of the root in response to iron deficiency, suggesting a role in buffering metal influx. Consistent with these roles, fpn2 has a diminished iron deficiency response, whereas fpn1 fpn2 has an elevated iron deficiency response. Ferroportins also play a role in cobalt homeostasis; a survey of Arabidopsis accessions for ionomic phenotypes showed that truncation of FPN2 results in elevated shoot cobalt levels and leads to increased sensitivity to the metal. Conversely, loss of FPN1 abolishes shoot cobalt accumulation, even in the cobalt accumulating mutant frd3. Consequently, in the fpn1 fpn2 double mutant, cobalt cannot move to the shoot via FPN1 and is not sequestered in the root vacuoles via FPN2; instead, cobalt likely accumulates in the root cytoplasm causing fpn1 fpn2 to be even more sensitive to cobalt than fpn2 mutants. PMID:19861554

  16. Lattice strain induced magnetism in substituted nanocrystalline cobalt ferrite

    NASA Astrophysics Data System (ADS)

    Kumar, Rajnish; Kar, Manoranjan

    2016-10-01

    Strontium (Sr) substituted cobalt ferrite i.e. Co1-xSrxFe2O4 (x=0.00, 0.01, 0.015, 0.02, 0.05, 0.1) have been synthesized by the citric acid modified sol-gel method. Crystal structure and phase purity have been studied by the X-ray powder diffraction technique. The Rietveld refinement of XRD pattern using the space group Fd 3 bar m shows monotonically increasing of lattice parameter with the increase in Sr concentration. Magnetic hysteresis loops measurement has been carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of ±1.5 T. Magnetocrystalline anisotropy constant were calculated by employing the Law of Approach (LA) to the saturation. It is observed that magnetocrystalline anisotropy has anomaly for x=0.01 (Co0.99Sr0.01Fe2O4) sample. Strain mediated modification of magnetic properties in Sr substituted cobalt ferrite has been observed. The saturation magnetization for doping concentration i.e. x=0.01 abruptly increase while for x>0.01 decreases with the increase in Sr concentration. A correlation between lattice strain and magnetic behavior in non-magnetic Sr- substituted nano-crystalline cobalt ferrite has been reported.

  17. Cesium and strontium ion specific exchangers

    SciTech Connect

    Yates, S.

    1996-10-01

    This work is one of two parallel projects that are part of an ESP task to develop high-capacity, selective, solid extractants for cesium, strontium, and technetium from nuclear wastes. In this subtask, Pacific Northwest National Laboratory (PNNL) is collaborating with AlliedSignal, Inc. (Des Plaines, Illinois) to develop inorganic ion exchangers that are selective for strontium and cesium from alkaline high-level waste and groundwater streams.

  18. Preparation of the Superconductor Substrate: Strontium Titanate

    DTIC Science & Technology

    1988-09-01

    single crystals of strontium titanate is derived from the original method developed by Verneuil . 16 The general procedure for the growth of single... crystals growth are reported. The growth direction was determined to be 5 degrees away from the [2111 direction. ICP-emission spectroscopy irdicates... Growth of Strontium Titanate Crystals 5 2.4 Preparation of Substrates 8 3. RESULTS AND CONCLUSIONS 8 REFERENCES 13 Illustrations 1. Schematic Diagram

  19. Mineral resource of the month: strontium

    USGS Publications Warehouse

    Ober, Joyce A.

    2008-01-01

    Last month as Americans sat transfixed watching fireworks on July 4, they were probably unaware that strontium was responsible for the beautiful reds in the display. Strontium, a soft silver-white or yellowish metallic element that turns yellow when exposed to air (and red when it burns), is prized for its brilliant red flame. Because it reacts with air and water, the metal is only present naturally in compounds, such as celestite and strontianite.

  20. Strontium ranelate for the management of osteoporosis.

    PubMed

    Lam, Sum; Zouzias, Katerina

    2008-07-01

    To evaluate the role of strontium ranelate in the management of osteoporosis. A MEDLINE (January 1966 to May 2007) search using the terms osteoporosis, strontium ranelate, bonemineral density, and fractures. All English-language articles identified from the data sources were evaluated. Strontium ranelate stimulates bone formation and inhibits bone resorption. Its safety and efficacy for osteoporosis were evaluated in four prospective, randomized, double-blind, placebo-controlled trials. The PREVOS (Prevention of Early Postmenopausal Bone Loss by Strontium Ranelate) trial suggested that 1 g daily is the optimal dose for preventing postmenopausal bone loss and was associated with a 1.41% increase in lumbar bone-mineral density (BMD). However, the STRATOS (Strontium Administration for Treatment of Osteoporosis) study found that a 1 g daily regimen was associated with a higher incidence of new vertebral deformities, and a 2 g daily regimen reduced lumbar BMD by 3% in postmenopausal, osteoporotic women. The SOTI (Spinal Osteoporosis Therapeutic Intervention) and TROPOS (Treatment of Peripheral Osteoporosis) studies suggested that a 2 g daily regimen reduced vertebral fractures by 39% to 41%, nonvertebral fractures by 16%, in postmenopausal, osteoporotic women. Most common adverse events reported were nausea and diarrhea. Four clinical trials demonstrated the efficacy and safety of strontium ranelate for the management of postmenopausal osteoporosis; however, the Food and Drug Administration has not approved it for this indication.

  1. Separation of strontium from fecal matter

    SciTech Connect

    Kester, D.K.

    1994-12-31

    The present invention relates to a method of separating strontium, and, more particularly, to a method of separating strontium from a sample of biomass potentially contaminated with various radionuclides. Radioactive strontium is a radionuclide which represents a hazard to man because of its long half-life and, if ingested, its tendency to be retained in the human body. In the event that radionuclides such as strontium or various actinides are ingested, it is desirable to monitor the discharge or release of these radionuclides from the human body through analysis of fecal matter. In laboratories and other facilities where potential for radionuclide contamination exists, fecal analysis for strontium is routinely conducted for individuals who are terminating from their position or are suspected of having been contaminated with radionuclides. Methods for separating and analyzing radioactive actinides from a biomass sample are well known and have been extensively developed for the US Department of Energy. These methods, described in the Department`s internal procedure, USDOE, RESL/ID, A-16, 1981, as well as in US Patent 5,190,881, involve the use of an iron phosphate precipitation step to separate actinides from a solution, or supernate. However, there are no established procedures for the separation of strontium from a biomass sample wherein an iron phosphate precipitation step is involved.

  2. Cobalt Cardiomyopathy: A Critical Reappraisal in Light of a Recent Resurgence.

    PubMed

    Packer, Milton

    2016-12-01

    Cobalt can cause a distinctive, rapidly progressive and reversible depression of cardiac systolic function, which is readily distinguished from other causes of cardiomyopathy. Patients present with the subacute onset of severe heart failure, which is accompanied by hypotension and cyanosis, pericardial effusion, low voltage on the electrocardiogram, marked elevation of serum enzymes, and lactic acidosis. They typically have a history of lethargy, anorexia, and weight loss in the months preceding the illness and exhibit other evidence of cobalt's effects on the body (eg, polycythemia and goiter). The course of cobalt-related cardiomyopathy may be progressive and fatal, but those who survive and cease exposure generally demonstrate complete resolution of symptoms and recovery of cardiac function. Patients presenting with rapid onset of cardiomyopathy, who also exhibit polycythemia, pericardial effusion, or goiter should be evaluated for cobalt exposure. Exposure can be confirmed by the measurement of cobalt in the serum, but serum levels of the ion are not reliably predictive of clinical cardiotoxicity. The clinical emergence of cobalt cardiomyopathy seems to require the coexistence of one or more cofactors, particularly a low-protein diet, thiamine deficiency, alcoholism, and hypothyroidism. As the medicinal use of cobalt has waned and measures to reduce industrial exposure have been implemented, subacute cobalt-related cardiomyopathy had become rare. However, reports describing classical features of the disease have recently surged among patients with a malfunctioning cobalt-alloy hip prosthesis. © 2016 American Heart Association, Inc.

  3. Halogenation of cobalt dicarbollide

    DOEpatents

    Hurlburt, P.K.; Abney, K.D.; Kinkead, S.A.

    1997-05-20

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10{prime} positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron. 1 fig.

  4. Halogenation of cobalt dicarbollide

    DOEpatents

    Hurlburt, Paul K.; Abney, Kent D.; Kinkead, Scott A.

    1997-01-01

    A method for selectively adding chlorine, bromine, or iodine to cobalt dicarbollide anions by means of electrophilic substitution reactions. Halogens are added only to the B10 and B10' positions of the anion. The process involves use of hypohalous acid or N-halosuccinimide or gaseous chlorine in the presence of iron.

  5. Coordination Complexes of Cobalt.

    ERIC Educational Resources Information Center

    Williams, Gregory M.; And Others

    1989-01-01

    Described is an experiment involving the synthesis and spectral studies of cobalt complexes that not only give general chemistry students an introduction to inorganic synthesis but allows them to conduct a systematic study on the effect of different ligands on absorption spectra. Background information, procedures, and experimental results are…

  6. Coordination Complexes of Cobalt.

    ERIC Educational Resources Information Center

    Williams, Gregory M.; And Others

    1989-01-01

    Described is an experiment involving the synthesis and spectral studies of cobalt complexes that not only give general chemistry students an introduction to inorganic synthesis but allows them to conduct a systematic study on the effect of different ligands on absorption spectra. Background information, procedures, and experimental results are…

  7. Hepatic cobalt and copper levels in lambs in Norway.

    PubMed

    Sivertsen, T; Plassen, C

    2004-01-01

    Cobalt and copper concentrations were measured in 599 lamb livers collected at slaughter from 58 sheep flocks in 6 different parts of Norway in 1993. Information about pasture, additional feeding and mineral supplements in the flocks was obtained through a questionnaire. Average hepatic levels of cobalt in the lamb flocks varied from < 0.003 to 0.22 microg/g ww, and of copper from 5 to 240 microg/g ww. Flocks with deficient or marginal cobalt status were found in all parts of southern Norway, but primarily in the west and south-west. Some flocks with marginal copper status were found in the south-west, while flocks with signs of excessive hepatic copper concentrations were found mainly in inner parts of central and northern Norway. Hepatic copper concentrations were significantly higher in lambs that had grazed mountain pastures than in those that had grazed lowland pastures in the summer.

  8. Persistant photoconductivity of strontium titanate

    NASA Astrophysics Data System (ADS)

    Poole, Violet Mary

    Strontium titanate (SrTiO3) is a transparent conducting oxide with a range of interesting properties, including a large, temperature-dependent dielectric constant and superconductivity at low temperatures. It has a wide indirect band gap of 3.2 eV at room temperature. Annealing in a reducing atmosphere with additional strontium oxide (SrO) powder at 1200°C results in the creation of native defects. These annealed samples show persistent photoconductivity (PPC) at room temperature, when exposed to light of energy 2.9 eV or greater. The three or more order of magnitude change in resistance persists long after the light is turned off. This effect is attributed to an electron being excited from an acceptor defect, with a large barrier for recapture, to the conduction band. This work investigates many of the changes that occur and factors that affect PPC. The right amount of SrO powder is crucial to the formation of PPC. The presence of some oxygen vacancies is also necessary for PPC; however, too many will mute the dramatic change in resistivity. Peaks at 430 nm and 520 nm appear in the visible region of the spectrum. The peak at 430 nm is due to iron, while the peak at 520 nm has not been identified. The infrared region of the spectrum also shows changes. First, the intensity of the transmitted signal drops significantly after light exposure, due to free carrier absorption. Additionally, a hydrogen line at 3500 cm-1 and satellites are often observed in as-received samples. The satellites disappear during annealing and return during PPC. The hydrogen lines have the same thermal kinetics as the 520 nm peak. Hydrogen lines at 3355 and 3384 cm-1, if present, will prevent PPC. An exposed chip can be erased (i.e. returned to its pre-light exposed state) by using a heat treatment. Erasing and polishing an annealed chip prior to light exposure can result in weakly p-type behavior with high mobility holes ( > 100 cm2/Vs). This is an order of magnitude higher than those

  9. OMCVD of cobalt and cobalt silicide

    NASA Astrophysics Data System (ADS)

    Dormans, G. J. M.; Meekes, G. J. B. M.; Staring, E. G. J.

    1991-11-01

    Cobalt and cobalt silicide layers were deposited by OMCVD using the Co precursors Co(C 5H 5) 2, Co 2(CO) 8, Co(C 5H 5)(CO) 2 and CoCF 3(CO) 4, and the Si precursors SiH 4 and Si 2H 6. Strongly textured (111)-β Co layers were grown from Co(C 5H 5) 2, Co(C 5H 5)(CO) 2 and CoCF 3(CO) 4 at temperatures above 300°C in H 2 at atmospheric pressure. Growth from Co(C 5H 5) 2 is inhibited on Si substrates. For temperatures ≥600°C the Co layers deposited from Co(C 5H 5)(CO) 2 react with the Si(100) substrate to form CoSi 2(00 l) aligned with the substrate orientation. Co 2(CO) 8 gives amorphous Co between 200 and 300°C. The upper temperature is set by the occurrence of homogeneous gas-phase reactions at atmospheric reactor pressure. Cobalt silicide layers can be grown from CO 2(CO) 8 and (di)silane at temperatures between 200 and 400°C. The Co/Si ratio in the layers decreases with increasing temperature and is independent of the gas-phase Co/Si ratio. Stoichiometric CoSi 2 is obtained at ~ 300°C. Both Co(C 5H 5) 2 and Co(C 5H 5)(CO) 2 react with (di)silane, leading to the incorporation of carbon in the layer. The Co/Si ration and the carbon content in the layers are practically independent of the deposition conditions. With CoCF 3(CO) 4 no contamination-free silicide could be grown. The carbon incorporation with Co(C 5H 5) 2 and Co(C 5H 5)(CO) 2 can be avoided by a pulsed growth method in which the Co precursor and the Si precursor are introduced alternately into the reactor. With Co(C 5H 5) 2 the growth is then inhibited on Si substrates.

  10. Cardiac concerns associated with strontium ranelate

    PubMed Central

    Reginster, Jean-Yves

    2014-01-01

    Introduction: Strontium ranelate is proven to reduce vertebral and non-vertebral fracture risk in osteoporosis. Concerns about cardiac safety have led to a new contraindication to strontium ranelate in patients with uncontrolled hypertension and/or current or past history of ischaemic heart disease, peripheral arterial disease and/or cerebrovascular disease. Areas covered: A literature search was performed; data were also collected from the European Medicines Agency website. Randomised controlled trial (RCT) data indicate a higher incidence of non-adjudicated myocardial infarction (MI) with strontium ranelate versus placebo (1.7 vs 1.1%; odds ratio [OR]: 1.6; 95% CI: 1.07 – 2.38; p = 0.020) (Mantel-Haenzel estimate of the OR). There was no increase in cardiovascular mortality. MI risk was mitigated by excluding patients with cardiovascular contraindications (OR: 0.99; 95% CI: 0.48 – 2.04; p = 0.988). Three observational studies performed in the context of real-life medical practice in the UK and Denmark did not report a signal. Expert opinion: The increased risk for cardiac events with strontium ranelate has been detected in RCTs but not in real life. Excluding patients with cardiovascular contraindications appears to be an effective measure for controlling the risk of MI. Strontium ranelate remains a useful therapeutic alternative in patients with severe osteoporosis without cardiovascular contraindications who are unable to take another osteoporosis treatment. PMID:25020233

  11. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section...

  12. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section...

  13. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this section...

  14. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this...

  15. 40 CFR 721.10598 - Lead strontium titanium zirconium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lead strontium titanium zirconium... Specific Chemical Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead strontium...

  16. 40 CFR 721.10598 - Lead strontium titanium zirconium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lead strontium titanium zirconium... Specific Chemical Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead strontium...

  17. Strontium Removal: Full-Scale Ohio Demonstrations | Science ...

    EPA Pesticide Factsheets

    The objectives of this presentation are to present a brief overview of past bench-scale research to evaluate the impact lime softening on strontium removal from drinking water and present full-scale drinking water treatment studies to impact of lime softening and ion exchange softening on strontium removal. To inform the public on strontium removal techniques

  18. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this...

  19. Specific activity and isotope abundances of strontium in purified strontium-82

    SciTech Connect

    Fitzsimmons, J. M.; Medvedev, D. G.; Mausner, L. F.

    2015-11-12

    A linear accelerator was used to irradiate a rubidium chloride target with protons to produce strontium-82 (Sr-82), and the Sr-82 was purified by ion exchange chromatography. The amount of strontium associated with the purified Sr-82 was determined by either: ICP-OES or method B which consisted of a summation of strontium quantified by gamma spectroscopy and ICP-MS. The summation method agreed within 10% to the ICP-OES for the total mass of strontium and the subsequent specific activities were determined to be 0.25–0.52 TBq mg-1. Method B was used to determine the isotope abundances by weight% of the purified Sr-82, and the abundances were: Sr-82 (10–20.7%), Sr-83 (0–0.05%), Sr-84 (35–48.5%), Sr-85 (16–25%), Sr-86 (12.5–23%), Sr-87 (0%), and Sr-88 (0–10%). The purified strontium contained mass amounts of Sr-82, Sr-84, Sr-85, Sr-86, and Sr-88 in abundances not associated with natural abundance, and 90% of the strontium was produced by the proton irradiation. A comparison of ICP-OES and method B for the analysis of Sr-82 indicated analysis by ICP-OES would be easier to determine total mass of strontium and comply with regulatory requirements. An ICP-OES analytical method for Sr-82 analysis was established and validated according to regulatory guidelines.

  20. Strontium-89 and Strontium-90 Levels in Breast Milk and in Mineral-Supplement Preparations

    PubMed Central

    Jarvis, Anita A.; Brown, John R.; Tiefenbach, Bella

    1963-01-01

    Strontium-90, strontium-89 and S.U. values were determined in human milk before and after the resumption of atmospheric nuclear testings in 1961, and the levels were compared to cows' milk values reported during the same time. S.U.90 levels in human milk were approximately one-fifth of those found in cows' milk. Assuming an average dietary intake of 11-13 S.U.90 during the period tested, the mean strontium/calcium ratio of 1.78 found in human milk represents an Observed Ratio milk-diet of approximately 0.14-0.16. Although strontium-89 was present in cows' milk already in September 1961, it did not appear in human milk until November 1961. It seems, therefore, that there was a two-month lag period between the appearance of fresh fallout in cows' milk and human milk. Calcium-supplement mineral preparations used by pregnant and lactating women were tested to find their strontium-89, strontium-90 and S.U. levels, because strontium isotopes, if present in these products, will be transferred to the fetus and to breast-fed infants. The compounds tested had S.U.90 levels of 0.13-2.62; in none of the preparations was Sr89 present. PMID:14041888

  1. Strontium hydroxyapatite and strontium carbonate as templates for the precipitation of calcium-phosphates in the absence and presence of fluoride

    NASA Astrophysics Data System (ADS)

    Sternitzke, Vanessa; Janousch, Markus; Heeb, Michèle B.; Hering, Janet G.; Johnson, C. Annette

    2014-06-01

    The heterogeneous precipitation of calcium-phosphates on calcium hydroxyapatite (Ca10(PO4)6(OH)2 or HAP) in the presence and absence of fluoride is important in the formation of bone and teeth, protection against tooth decay, dental and skeletal fluorosis and defluoridation of drinking water. Strontium hydroxyapatite (Sr10(PO4)6(OH)2 or SrHAP) and strontium carbonate (SrCO3) were used as calcium-free seed templates in precipitation experiments conducted with varying initial calcium-to-phosphate (Ca/P) or calcium-to-phosphate-to-fluoride (Ca/P/F) ratios. Suspensions of SrHAP or SrCO3 seed templates (which were calcium-limited for both templates and phosphate-limited in the case of SrCO3) were reacted at pH 7.3 (25 °C) over 3 days. The resulting solids were examined with Scanning Transmission Electron Microscopy (STEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure (XANES), and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS). Calcium apatite was the predominant phase identified by all techniques independent of the added Ca/P ratios and of the presence of fluoride. It was not possible to make an unambiguous distinction between HAP and fluorapatite (Ca10(PO4)6F2, FAP). The apatite was calcium-deficient and probably contained some strontium.

  2. Enhanced magnetic trap loading for atomic strontium

    NASA Astrophysics Data System (ADS)

    Barker, D. S.; Reschovsky, B. J.; Pisenti, N. C.; Campbell, G. K.

    2015-10-01

    We report on a technique to improve the continuous loading of atomic strontium into a magnetic trap from a magneto-optical trap. This is achieved by adding a depumping laser tuned to the P31→S31 (688-nm) transition. The depumping laser increases atom number in the magnetic trap and subsequent cooling stages by up to 65% for the bosonic isotopes and up to 30% for the fermionic isotope of strontium. We optimize this trap loading strategy with respect to the 688-nm laser detuning, intensity, and beam size. To understand the results, we develop a one-dimensional rate equation model of the system, which is in good agreement with the data. We discuss the use of other transitions in strontium for accelerated trap loading and the application of the technique to other alkaline-earth-like atoms.

  3. Cobalt sorption in silica-pillared clays.

    PubMed

    Sampieri, A; Fetter, G; Bosch, P; Bulbulian, S

    2006-01-03

    Silicon pillared samples were prepared following conventional and microwave irradiation methods. The samples were characterized and tested in cobalt sorption. Ethylenediammine was added before cobalt addition to improve the amount of cobalt retained. The amount of cobalt introduced in the original clay in the presence of ethylenediammine was the highest. In calcined pillared clays the cobalt retention with ethylenediammine was lower (ca. 40%). In all cases the presence of ethylenediammine increased twice the amount of cobalt sorption measured for aqueous solutions.

  4. Bioaccessibility testing of cobalt compounds.

    PubMed

    Stopford, Woodhall; Turner, John; Cappellini, Danielle; Brock, Tom

    2003-08-01

    Testing of metal compounds for solubility in artificial fluids has been used for many years to assist determining human health risk from exposure to specific compounds of concern. In lieu of obtaining bioavailability data from samples of urine, blood, or other tissues, these studies measured solubility of compounds in various artificial fluids as a surrogate for bioavailability. In this context, the measurement of metal "bioaccessibility" can be used as an in vitro substitute for measuring metal bioavailability. Bioaccessibility can be defined as a value representing the availability of metal for absorption when dissolved in in vitro surrogates of body fluids or juices. The aim of this study was to measure and compare the bioaccessibility of selected cobalt compounds in artificial human tissue fluids and human serum. A second aim was to initiate studies to experimentally validate an in vitro methodology that would provide a conservative estimate of cobalt bioavailability in the assessment of dose from human exposure to various species of cobalt compounds. This study evaluated the bioaccessibility of cobalt(II) from 11 selected cobalt compounds and an alloy in 2 physical forms in 5 surrogate human tissue fluids and human serum. Four (4) separate extraction times were used up to 72 hours. The effect of variables such as pH, dissolution time, and mass-ion effect on cobalt bioaccessibility were assessed as well. We found that the species of cobalt compound as well as the physico-chemical properties of the surrogate fluids, especially pH, had a major impact on cobalt solubility. Cobalt salts such as cobalt(II) sulfate heptahydrate were highly soluble, whereas cobalt alloys used in medical implants and cobalt aluminate spinels used as pigments, showed minimal dissolution over the period of the assay.

  5. Thermodynamic restrictions on mechanosynthesis of strontium titanate

    SciTech Connect

    Monteiro, J.F.; Ferreira, A.A.L.; Antunes, I.; Fagg, D.P.; Frade, J.R.

    2012-01-15

    Chemical potential phase stability diagrams were calculated from relevant thermodynamic properties and used to predict the thermodynamic driving force under prospective conditions of room temperature mechanosynthesis. One analysed the dependence of chemical potential diagrams on temperature and partial pressure of evolving gases such as oxygen or carbon dioxide, as expected on using strontium peroxide or strontium carbonate as precursor reactants for the alkali earth component. Thermodynamic calculations were also obtained for changes in titania precursor reactants, including thermodynamic predictions for reactivity of strontium carbonate with amorphous titania. Experimental evidence showed that strontium titanate can be obtained by mechanosynthesis of strontium carbonate+anatase mixtures, due to previous amorphization under high energy milling. Ability to perform mechanosynthesis with less energetic milling depends on the suitable choice of alternative precursor reactants, which meet the thermodynamic requirements without previous amorphization; this was demonstrated by mechanosynthesis from anatase+strontium peroxide mixtures. - Graphical abstract: X-Ray diffractograms of the starting TiO{sub 2} (anatase)+SrCO{sub 3} mixture and after mechanical activation at 650 rpm, for 1, 2, and 7 h. Different symbols are used to identify reflections ascribed to anatase (diamonds), SrCO{sub 3} (squares) and SrTiO{sub 3} (triangles). Highlights: Black-Right-Pointing-Pointer Prediction of thermodynamic driving force for room temperature mechanosynthesis. Black-Right-Pointing-Pointer Dependence of chemical potential diagrams on temperature and partial pressure. Black-Right-Pointing-Pointer Thermodynamic calculations for changes in titania precursor. Black-Right-Pointing-Pointer Experimental support for thermodynamic predictions.

  6. Cobalt ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1983-01-01

    Varying concentrations of an organometallic cobalt complex were added to an epoxy system currently used by the aerospace industry as a composite matrix resin. Methods for combining cobalt (III) acetylacetonate with a tetraglycidyl 4,4 prime - diaminodiphenylmethane-based epoxy were investigated. The effects of increasing cobalt ion concentration on the epoxy cure were demonstrated by epoxy gel times and differential scanning calorimetry cure exotherms. Analysis on cured cobalt-containing epoxy castings included determination of glass transition temperatures by thermomechanical analysis, thermooxidative stabilities by thermogravimetric analysis, and densities in a density gradient column. Flexural strength and stiffness were also measured on the neat resin castings.

  7. First principles investigation of substituted strontium hexaferrite

    NASA Astrophysics Data System (ADS)

    Dixit, Vivek

    This dissertation investigates how the magnetic properties of strontium hexaferrite change upon the substitution of foreign atoms at the Fe sites. Strontium hexaferrite, SrFe12O19, is a commonly used hard magnetic material and is produced in large quantities (around 500,000 tons per year). For different applications of strontium hexaferrite, its magnetic properties can be tuned by a proper substitution of the foreign atoms. Experimental screening for a proper substitution is a cost-intensive and time-consuming process, whereas computationally it can be done more efficiently. We used the 'density functional theory' a first principles based method to study substituted strontium hexaferrite. The site occupancies of the substituted atoms were estimated by calculating the substitution energies of different configurations. The formation probabilities of configurations were used to calculate the magnetic properties of substituted strontium hexaferrite. In the first study, Al-substituted strontium hexaferrite, SrFe12-x AlxO19 with x=0.5 and x=1.0 were investigated. It was found that at the annealing temperature the non-magnetic Al +3 ions preferentially replace Fe+3 ions from the 12 k and 2a sites. We found that the magnetization decreases and the magnetic anisotropy field increases as the fraction, x of the Al atoms increases. In the second study, SrFe12-xGaxO19 and SrFe12-xInxO19 with x=0.5 and x=1.0 were investigated. In the case of SrFe12-xGaxO19, the sites where Ga+3 ions prefer to enter are: 12 k, 2a, and 4f1. For SrFe12-xInxO19, In+3 ions most likely to occupy the 12k, 4f1 , and 4f2 sites. In both cases the magnetization was found to decrease slightly as the fraction of substituted atom increases. The magnetic anisotropy field increased for SrFe12-xGaxO 19, and decreased for SrFe12-xInxO19 as the concentration of substituted atoms increased. In the third study, 23 elements (M) were screened for their possible substitution in strontium hexaferrite, SrFe12-xMxO 19

  8. Morphology Tuning of Strontium Tungstate Nanoparticles

    SciTech Connect

    Joseph, S.; George, T.; George, K. C.; Sunny, A. T.; Mathew, S.

    2007-08-22

    Strontium tungstate nanocrystals in two different morphologies are successfully synthesized by controlled precipitation in aqueous and in poly vinyl alcohol (PVA) medium. Structural characterizations are carried out by XRD and SEM. The average particle size calculated for the SrWO4 prepared in the two different solvents ranges 20-24 nm. The SEM pictures show that the surface morphologies of the SrWO4 nanoparticles in aqueous medium resemble mushroom and the SrWO4 nanoparticles in PVA medium resemble cauliflower. Investigations on the room temperature luminescent properties of the strontium tungstate nanoparticles prepared in aqueous and PVA medium shows strong emissions around 425 nm.

  9. Dioxygen bound cobalt corroles.

    PubMed

    Mittra, Kaustuv; Mondal, Biswajit; Mahammed, Atif; Gross, Zeev; Dey, Abhishek

    2017-01-10

    Two cobalt-dioxygen adducts, [CoH8]-O2 and [CoCl8]-O2, chelated by electron-rich and electron-poor corroles, respectively, were isolated in solution. Characterization by resonance Raman (rR) and EPR spectroscopy, together with DFT analyses, point towards (corrole) cobalt(iii)-O2˙(-) structures in both cases. The most significant insight was obtained from the Co-O and O-O stretching frequencies, which revealed that the Co-O bond in [CoH8]-O2 is somewhat stronger than in [CoCl8]-O2 and its O-O is weaker, but also that the differences are truly minute (8-10 cm(-1) for the O-O stretch). These conclusions are vital regarding the various applications that rely on efficient reduction of molecular oxygen. In particular, these kinds of cobalt complexes are perfectly suited for serving as electrocatalysts that may be tuned to operate at minimal overpotential without losing almost anything in terms of activity.

  10. Controls over the strontium isotope composition of river water

    SciTech Connect

    Palmer, M.R. ); Edmond, J.M. )

    1992-05-01

    Strontium concentrations and isotope ratios have been measured in river and ground waters from the Granges, Orinoco, and Amazon river basins. When compared with major element concentrations, the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments: (1) typical drainage basins containing limestones, evaporites, shales, and alumino-silicate metamorphic and igneous rocks; (2) shield terrains containing no chemical or biogenic sediments; and (3) the flood plains that constitute the largest areas of many large rivers. The strontium concentration and isotope compositions of river waters are largely defined by mixing of strontium derived from limestones and evaporites with strontium derived from silicate rocks. The strontium isotope composition of the limestone end member generally lies within the Phanerozoic seawater range, which buffers the [sup 87]Sr/[sup 86]Sr ratios of major rivers. A major exception is provided by the rivers draining the Himalayas, where widescale regional metamorphism appears to have led to an enrichment in limestones of radiogenic strontium derived from coexisting silicate rocks. The strontium isotope systematics of rivers draining shield areas are controlled by the intense, transport-limited, nature of the weathering reactions, and thereby limits variations in the strontium flux from these terrains. Flood plains are only a minor source of dissolved strontium to river waters, and precipitation of soil salts in some flood plains can reduce the riverine flux of dissolved strontium to the oceans.

  11. Superior real-time holographic storage properties in doped potassium sodium strontium barium niobate crystal.

    PubMed

    Li, Y; Liu, S; Yang, M; Yang, K; Xu, K; Hou, F

    1997-02-15

    We demonstrate superior holographic storage performance in a cobalt doped potassium sodium strontium barium niobate (Co:KNSBN) crystal that possesses a fast response time of 1.4 ms, a large photorefractive sensitivity of 13 x 10(-3) cm(3) J(-1) under a total writing intensity of 1 W/cm(2) , and high spatial resolution of 45 line pairs/mm. Reconstructed images with high fidelity have been obtained in real-time holographic storage. The dynamic properties of the index grating, the dependence of response time on writing intensity, and the dark decay of diffraction signal with increased writing intensity indicate that two species and shallow traps exist in Co:KNSBN crystal.

  12. Strontium Removal: Full-Scale Ohio Demonstrations

    EPA Science Inventory

    The objectives of this presentation are to present a brief overview of past bench-scale research to evaluate the impact lime softening on strontium removal from drinking water and present full-scale drinking water treatment studies to impact of lime softening and ion exchange sof...

  13. Cesium and Strontium Separation Technologies Literature Review

    SciTech Connect

    T. A. Todd; T. A. Todd; J. D. Law; R. S. Herbst

    2004-03-01

    Integral to the Advanced Fuel Cycle Initiative (AFCI) Program’s proposed closed nuclear fuel cycle, the fission products cesium and strontium in the dissolved spent nuclear fuel stream are to be separated and managed separately. A comprehensive literature survey is presented to identify cesium and strontium separation technologies that have the highest potential and to focus research and development efforts on these technologies. Removal of these high-heat-emitting fission products reduces the radiation fields in subsequent fuel cycle reprocessing streams and provides a significant short-term (100 yr) heat source reduction in the repository. This, along with separation of actinides, may provide a substantial future improvement in the amount of fuel that could be stored in a geologic repository. The survey and review of the candidate cesium and strontium separation technologies are presented herein. Because the AFCI program intends to manage cesium and strontium together, technologies that simultaneously separate both elements are of the greatest interest, relative to technologies that separate only one of the two elements.

  14. Strontium Removal: Full-Scale Ohio Demonstrations

    EPA Science Inventory

    The objectives of this presentation are to present a brief overview of past bench-scale research to evaluate the impact lime softening on strontium removal from drinking water and present full-scale drinking water treatment studies to impact of lime softening and ion exchange sof...

  15. Strontium Isotopes and Magma Dynamics

    NASA Astrophysics Data System (ADS)

    Wolff, J. A.; Ellis, B. S.; Ramos, F. C.

    2010-12-01

    Over the past decade, it has become clear that volcanic rocks commonly exhibit internal heterogeneity in radiogenic isotopes. In particular, strontium isotopic disequilibrium between co-exisitng phenocrysts, between phenocrysts and matrix, and isotopic zoning within single crystals has been demonstrated in basalts, andesites, dacites, rhyolites and alkaline magmas; in some cases, the range in 87Sr/86Sr among different components in the same rock may equal or exceed the bulk-rock range seen in the entire formation, volcanic center, or province. High-temperature “Snake River type” rhyolites appear to be an exception. Despite the occurrence of Snake River Plain rhyolites in a region of isotopically highly variable crust and mantle, and significant differences from rhyolite unit to rhyolite unit, internally they are near-homogeneous in 87Sr/86Sr. Little or no zoning is found within feldspar phenocrysts, and feldspars within a single unit are tightly grouped. Some units show minor contrasts between phenocrysts and matrix. High temperature rhyolitic magmas possess a unique combination of temperature and melt viscosity. Although they are typically 200°C hotter than common rhyolites, the effect on visocity is offset by lower water contents (~2 wt%), hence their melt viscosities are in the same range as common, water-rich, cool rhyolites (105 - 106 Pa s). Yet magmatic temperatures are in the same range as basaltic andesites and andesites, consequently cation diffusion rates in feldspar are 2 - 3 orders of magnitude greater than in common rhyolites. We hypothesize that this combination of characteristics promotes Sr isotopic homogeneity: high melt viscosities tend to inhibit crystal transfer and mixing of isotopically distinct components on timescales shorter than those required for diffusive homogenization of Sr between phenocrysts and matrix (100 - 1000 years). This is not the case for most magmas, in which either crystal transfer is rapid (<< 100 years) due to low

  16. Strontium ranelate increases osteoblast activity.

    PubMed

    Almeida, Monica Marletti; Nani, Edson Parra; Teixeira, Lucas Novaes; Peruzzo, Daiane Cristina; Joly, Júlio César; Napimoga, Marcelo Henrique; Martinez, Elizabeth Ferreira

    2016-06-01

    Strontium ranelate (SR) is the first generation of a new class of medication for osteoporosis, which is capable of inducing bone formation and, to a certain extent, inhibiting bone resorption. The aim of this study was to evaluate the in vitro effects of SR on osteoblastic cell cultures. MC3TE-E1 cells were seeded in 24-well plates at a density of 2×10(4) cells/well and exposed to SR at 0.05, 0.1, and 0.5mM. The following parameters were assayed: 1) Cell proliferation by hemocytometer counting after 24, 48 and 72h, 2) Cell viability by MTT assay after 24, 48 and 72h, 3) Type I Collagen and Osteopontin (OPN) quantification by Western Blotting, ELISA, and Real Time PCR after 48h, 3) Immunolocalization of fibronectin (FN) by epifluorescence, and 4) matrix mineralization by Alizarin Red staining after 14days. After 24, 48 and 72h, the cell proliferation and viability were not affected by SR at 0.05 and 0.1mM (p>0.05). However, cell cultures exposed to SR at 0.5mM exhibited a decrease in both cell proliferation and cell viability in all time points assayed (p<0.05). High levels of protein and mRNA for Type I Collagen and OPN were detected in cultures exposed to SR, particularly at 0.5mM (p<0.05). SR allowed the expression of FN in osteoblastic cell cultures as observed by epifluorescence analysis. The mineralized bone-like nodule formation was affected in a concentration-dependent manner by SR, with large bone-like nodules being detected in osteoblastic cell cultures exposed to SR at 0.5mM. In conclusion, these results suggest that SR can accelerate acquisition of the osteoblastic phenotype, which explains, at least in part, the rebalancing of bone turnover in favor of bone formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Effects of calcium and magnesium on strontium distribution coefficients

    USGS Publications Warehouse

    Bunde, R.L.; Rosentreter, J.J.; Liszewski, M.J.; Hemming, C.H.; Welhan, J.

    1997-01-01

    The effects of calcium and magnesium on the distribution of strontium between a surficial sediment and simulated wastewater solutions were measured as part of an investigation to determine strontium transport properties of surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. The investigation was conducted by the U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy. Batch experimental techniques were used to determine strontium linear sorption isotherms and distribution coefficients (K(d)'s) using simulated wastewater solutions prepared at pH 8.0??0.1 with variable concentrations of calcium and magnesium. Strontium linear sorption isotherm K(d)'s ranged from 12??1 to 85??3 ml/g, increasing as the concentration of calcium and magnesium decreased. The concentration of sorbed strontium and the percentage of strontium retained by the sediment were correlated to aqueous concentrations of strontium, calcium, and magnesium. The effect of these cation concentrations on strontium sorption was quantified using multivariate least-squares regression techniques. Analysis of data from these experiments indicates that increased concentrations of calcium and magnesium in wastewater discharged to waste disposal ponds at the INEL increases the availability of strontium for transport beneath the ponds by decreasing strontium sorption to the surficial sediment.

  18. Cobalt source calibration

    SciTech Connect

    Rizvi, H.M.

    1999-12-03

    The data obtained from these tests determine the dose rate of the two cobalt sources in SRTC. Building 774-A houses one of these sources while the other resides in room C-067 of Building 773-A. The data from this experiment shows the following: (1) The dose rate of the No.2 cobalt source in Building 774-A measured 1.073 x 10{sup 5} rad/h (June 17, 1999). The dose rate of the Shepherd Model 109 Gamma cobalt source in Building 773-A measured 9.27 x 10{sup 5} rad/h (June 25, 1999). These rates come from placing the graduated cylinder containing the dosimeter solution in the center of the irradiation chamber. (2) Two calibration tests in the 774-A source placed the graduated cylinder with the dosimeter solution approximately 1.5 inches off center in the axial direction. This movement of the sample reduced the measured dose rate 0.92% from 1.083 x 10{sup 5} rad/h to 1.073 x 10{sup 5} rad/h. and (3) A similar test in the cobalt source in 773-A placed the graduated cylinder approximately 2.0 inches off center in the axial direction. This change in position reduced the measured dose rate by 10.34% from 1.036 x 10{sup 6} to 9.27 x 10{sup 5}. This testing used chemical dosimetry to measure the dose rate of a radioactive source. In this method, one determines the dose by the chemical change that takes place in the dosimeter. For this calibration experiment, the author used a Fricke (ferrous ammonium sulfate) dosimeter. This solution works well for dose rates to 10{sup 7} rad/h. During irradiation of the Fricke dosimeter solution the Fe{sup 2+} ions ionize to Fe{sup 3+}. When this occurs, the solution acquires a slightly darker tint (not visible to the human eye). To determine the magnitude of the change in Fe ions, one places the solution in an UV-VIS Spectrophotometer. The UV-VIS Spectrophotometer measures the absorbency of the solution. Dividing the absorbency by the total time (in minutes) of exposure yields the dose rate.

  19. NMR study of strontium binding by a micaceous mineral.

    PubMed

    Bowers, Geoffrey M; Ravella, Ramesh; Komarneni, Sridhar; Mueller, Karl T

    2006-04-13

    The nature of strontium binding by soil minerals directly affects the transport and sequestration/remediation of radioactive strontium species released from leaking high-level nuclear waste storage tanks. However, the molecular-level structure of strontium binding sites has seldom been explored in phyllosilicate minerals by direct spectroscopic means and is not well-understood. In this work, we use solid-state NMR to analyze strontium directly and indirectly in a fully strontium-exchanged synthetic mica of nominal composition Na(4)Mg(6)Al(4)Si(4)O(20)F(4). Thermogravimetric analysis, X-ray diffraction analysis, and NMR evidence supports that heat treatment at 500 degrees C for 4 h fully dehydrates the mica, creating a hydrogen-free interlayer. Analysis of the strontium NMR spectrum of the heat-treated mica shows a single strontium environment with a quadrupolar coupling constant of 9.02 MHz and a quadrupolar asymmetry parameter of 1.0. These quadrupolar parameters are consistent with a highly distorted and asymmetric coordination environment that would be produced by strontium cations without water in the coordination sphere bound deep within the ditrigonal holes. Evidence for at least one additional strontium environment, where proton-strontium couplings may occur, was found via a (1)H-(87)Sr transfer of populations by double resonance NMR experiment. We conclude that the strontium cations in the proton-free interlayer are observable by (87)Sr NMR and bound through electrostatic interactions as nine coordinate inner-sphere complexes sitting in the ditrigonal holes. Partially hydrated strontium cations invisible to direct (87)Sr NMR are also present and located on the external mica surfaces, which are known to hydrate upon exposure to atmospheric moisture. These results demonstrate that modern pulsed NMR techniques and high fields can be used effectively to provide structural details of strontium binding by phyllosilicate minerals.

  20. NMR Study of Strontium Binding by a Micaceous Mineral

    SciTech Connect

    Bowers, Geoffrey M.; Ravella, Ramesh; Komarneni, S.; Mueller, Karl T.

    2006-04-13

    The nature of strontium binding by soil minerals directly affects the transport and sequestration/remediation of radioactive strontium species released from leaking high-level nuclear waste storage tanks. However, the molecular-level structure of strontium binding sites has seldom been explored in phyllosilicate minerals by direct spectroscopic means and is not well-understood. In this work, we use solid-state NMR to analyze strontium directly and indirectly in a fully strontium-exchanged synthetic mica of nominal composition Na4Mg6Al4Si4O20F4. Thermogravimetric analysis, X-ray diffraction analysis, and NMR evidence supports that heat treatment at 500 °C for 4 h fully dehydrates the mica, creating a hydrogen-free interlayer. Analysis of the strontium NMR spectrum of the heat-treated mica shows a single strontium environment with a quadrupolar coupling constant of 9.02 MHz and a quadrupolar asymmetry parameter of 1.0. These quadrupolar parameters are consistent with a highly distorted and asymmetric coordination environment that would be produced by strontium cations without water in the coordination sphere bound deep within the ditrigonal holes. Evidence for at least one additional strontium environment, where proton-strontium couplings may occur, was found via a 1H-87Sr transfer of populations by double resonance NMR experiment. We conclude that the strontium cations in the proton-free interlayer are observable by 87Sr NMR and bound through electrostatic interactions as nine coordinate inner-sphere complexes sitting in the ditrigonal holes. Partially hydrated strontium cations invisible to direct 87Sr NMR are also present and located on the external mica surfaces, which are known to hydrate upon exposure to atmospheric moisture. These results demonstrate that modern pulsed NMR techniques and high fields can be used effectively to provide structural details of strontium binding by phyllosilicate minerals.

  1. Thermochemistry of perovskites in the lanthanum-strontium-manganese-iron oxide system

    NASA Astrophysics Data System (ADS)

    Marinescu, Cornelia; Vradman, Leonid; Tanasescu, Speranta; Navrotsky, Alexandra

    2015-10-01

    The enthalpies of formation from binary oxides of perovskites (ABO3) based on lanthanum strontium manganite La(Sr)MnO3 (LSM) and lanthanum strontium ferrite La(Sr)FeO3 (LSF) and mixed lanthanum strontium manganite ferrite La(Sr)Mn(Fe)O3 (LSMF) were measured by high temperature oxide melt solution calorimetry. Using iodometric titration, the oxygen content was derived. The perovskites with A-site cation deficiency have greater oxygen deficiency than the corresponding A-site stoichiometric series. Stability of LSMF decreases with increasing iron content. Increasing oxygen deficiency clearly destabilizes the perovskites. The results suggest an enthalpy of oxygen incorporation that is approximately independent of composition. 0.35La2O3 (xl, 25 °C)+Mn2O3 (xl, 25 °C)+0.3SrO (xl, 25 °C)+Fe2O3 (xl, 25 °C)+O2 (g, 25 °C)→La0.7Sr0.3Mn1-yFeyO3-δ (xl, 25 °C). (b) ∆ Hf,ox* (La0.7Sr0.3Mn1-yFeyO3-δ) .0.35 La2O3 (xl, 25 ººC) + (0.7-y+ 2δ)/2 Mn2O3 (xl, 25 ºC) + 0.3 SrO (xl, 25 ºC) + y/2Fe2O3 (xl, 25 ºC) + (0.3-2δ) MnO2 (xl, 25 ºC)→La0.7Sr0.3Mn1-yFeyO3-δ (xl, 25 ºC).

  2. The Universal Solvent Extraction (UNEX) Process I: Development of the UNEX Process Solvent for the Separation of Cesium, Strontium, and the Actinides from Acidic Radioactive Waste

    SciTech Connect

    Law, Jack Douglas; Todd, Terry Allen; Herbst, Ronald Scott; Brewer, Ken Neal; Romanovskiy, V. N.; Smirnov, I. V.; Babain, V. A.

    2001-01-01

    A synergistic extraction mixture containing chlorinated cobalt dicarbollide (CCD), carbamoylmethyl phosphine oxide (CMPO), and polyethylene glycol (PEG) has been investigated for the simultaneous recovery of cesium, strontium, lanthanides, and actinides from highly acidic media. The extraction properties of this mixture depend on the concentration ratio of the components. For recovery of all major radionuclides, the optimal ratio of [CCD]:[PEG]: [CMPO] = 5:1:1 should be used. The use of diphenyl-N,N-dibutylcarbamoylmethyl phosphine oxide and PEG-400 provides the most efficient recovery of cesium, strontium, lanthanides, and actinides. The possibility of using polyfluorinated ethers, esters, ketones, and sulfones as diluents was examined. Phenyltrifluoromethyl sulfone was the most suitable diluent tested. The use of this diluent allows good extraction properties, chemical and radiation stability, excellent explosion/fire-safety properties, and favorable hydrodynamic characteristics. The extraction of radionuclides from HNO3 media by mixtures of CCD:PEG:CMPO in phenyltrifluoromethyl sulfone and the subsequent stripping behavior were evaluated.

  3. Strontium biokinetic model for mouse-like rodent.

    PubMed

    Malinovsky, Georgy; Yarmoshenko, Ilia; Zhukovsky, Michael; Starichenko, Vera; Modorov, Makar

    2013-04-01

    Model describing the biokinetics of strontium for murine rodent is suggested. The model represents modification of the ICRP model for reference human with reduced number of compartments: Blood, Gastrointestinal tract, Soft tissues, Skeleton, Urinary bladder. To estimate transfer rates of the model the published experimental data on strontium retention in body of laboratory and wild mice were analyzed. A set of eleven transfer rates suggested for the strontium biokinetic model for murine rodent satisfactorily describes both the laboratory experiments (relative standard error of 9.5%) and data on radiostrontium content available for wild animals. Application of the model allows estimation of strontium distribution by organs and tissues both in the cases of acute and chronic exposure with assessment of strontium activity in organs with time since beginning of exposure. The developed strontium biokinetic model will be used for internal dose assessment for murine rodents inhabiting East-Ural Radioactive Trace, where (90)Sr intake is a significant source of contemporary internal exposure.

  4. Controls over the strontium isotope composition of river water

    NASA Astrophysics Data System (ADS)

    Palmer, M. R.; Edmond, J. M.

    1992-05-01

    Strontium concentrations and isotope ratios have been measured in river and ground waters from the Ganges, Orinoco, and Amazon river basins. When compared with major element concentrations, the data set has allowed a detailed examination of the controls over the strontium isotope systematics of riverine input to the oceans in the following environments: (1) "typical" drainage basins containing limestones, evaporites, shales, and alumino-silicate metamorphic and igneous rocks; (2) shield terrains containing no chemical or biogenic sediments; and (3) the floodplains that constitute the largest areas of many large rivers. The strontium concentration and isotope composition of river waters are largely defined by mixing of strontium derived from limestones and evaporites with strontium derived from silicate rocks. The strontium isotope composition of the limestone endmember generally lies within the Phanerozoic seawater range, which buffers the 87Sr /86Sr ratios of major rivers. A major exception is provided by the rivers draining the Himalayas, where widescale regional metamorphism appears to have led to an enrichment in limestones of radiogenic strontium derived from coexisting silicate rocks. The strontium isotope systematics of rivers draining shield areas are controlled by the intense, transportlimited, nature of the weathering reactions, and thereby limits variations in the strontium flux from these terrains. Floodplains are only a minor source of dissolved strontium to river waters, and precipitation of soil salts in some floodplains can reduce the riverine flux of dissolved strontium to the oceans. The most effective mechanisms for altering the isotope ratio and flux of riverine strontium to the oceans are increased glaciation and large-scale regional metamorphism of the type produced during continental collision. Both mechanisms provide a means for increasing the 87Sr /86Sr ratio of the global riverine flux.

  5. Strontium metabolism in the rebuilding of skeletal tissue

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The relationship between calcium and strontium in bone metabolism is described. Whole body comparisons in the form of balance studies, plasma kinetics, and biochemical bone differences are briefly reviewed. The value of strontium as a qualitative calcium mimetic is established. A procedure of strontium deposition in the bones is presented as a means to study postflight bone rebuilding and to locate areas of inflight demineralization.

  6. Phase Stability of the Lanthanum Strontium Manganites

    NASA Astrophysics Data System (ADS)

    Zheng, Feng; Pederson, Larry

    1996-03-01

    Phase diagram and thermodynamic data of the La-Sr-Mn-O system has been studied. The ABO3 -type perovskite of this system is presently the preferred cathode material for application in solid oxide fuel cells. And the phase stability of the lanthanum strontium manganites at elevated temperature is vital to fuel cell operation. Measuring the electromotive force through solid galvanic cell (-) Air,Pt|SrF_2,SrO||CaF_2||La_1-xSr_xMnO_3,SrF_2|Pt,Air (+) and the like enable us to derive the strontium oxide activity and other thermodynamic parameters such as Gibbs free energy of reaction, etc, which help us to understand the materials in using.

  7. Removal of Strontium from Drinking Water by Conventional ...

    EPA Pesticide Factsheets

    The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. There is very little data available on strontium removal from drinking water. As a result, there is an immediate need to perform treatment studies. The objective of this work is to evaluate the effectiveness of conventional and lime-soda ash softening treatments to remove strontium from surface and ground waters. Conventional drinking water treatment with aluminum and iron coagulants were able to achieve 12% and 5.9% strontium removal at best, while lime softening removed as much as 78% from natural strontium-containing ground water. Systematic fundamental experiments showed that strontium removal during the lime-soda ash softening was related to pH, calcium concentration and dissolved inorganic carbon concentration. Final strontium concentration was also directly associated with initial strontium concentration. Precipitated solids showed well-formed crystals or agglomerates of mixed solids, two polymorphs of calcium carbonate (vaterite and calcite), and strontianite, depending on initial water quality conditions. X-ray diffraction analysis suggested that strontium likely replaced calcium inside the crystal lattice and was likely mainly responsible for removal during lime softening. To inform the public.

  8. Lanthanide doped strontium-barium cesium halide scintillators

    DOEpatents

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  9. Fractionation of strontium isotopes in cation-exchange chromatography

    SciTech Connect

    Oi, Takao; Ogino, Hideki; Kakihana, Hidetake ); Hosoe, Morikazu )

    1992-04-01

    Strontium isotope fractionation has been observed in cation-exchange chromatography of strontium salts. The heavier isotopes have been found enriched at the front parts of displacement-type chromatograms, which means that the heavier isotopes are preferentially fractionated into the solution phase. The average values of the single-stage separation factor (S) minus one per unit mass difference between isotopes have been 1.0 {times} 10{sup {minus}6} for the strontium chloride system, 2.9 {times} 10{sup {minus}6} for the strontium acetate system, and 3.1 {times} 10{sup {minus}6} for the strontium lactate system at 25C. No evidence of the odd-even anomalous isotope effects has been observed. The isotopic reduced partition function ratios (RPFRs) of the strontium species involved in the present study have been estimated; the RPFRs of the complex species have been found to be larger than that of simple hydrated strontium lactate and strontium acetate systems are larger than that of the strontium chloride system.

  10. Origin of absorption peaks in reflection loss spectrum in Ku- frequency band of Co-Zr substituted strontium hexaferrites prepared using sucrose precursor

    NASA Astrophysics Data System (ADS)

    Narang, Sukhleen Bindra; Pubby, Kunal; Chawla, S. K.; Kaur, Prabhjyot

    2017-03-01

    This study presents the detailed explanation of the factors, contributing towards the absorption peaks in reflection loss spectrum of hexaferrites. Cobalt-Zirconium substituted strontium hexaferrites, synthesized using sucrose precursor sol-gel technique, were analyzed in 12.4-18 GHz frequency range. The concepts of impedance matching through quarter wavelength condition, complex thickness, dielectric phase angle and attenuation constant have been used to determine the location as well as intensity of absorption peaks. This study also demonstrates the potential application of three compositions of this series with doping content (x)==0.0, 0.6 and 0.8 as an effective microwave absorbers in Ku-frequency band.

  11. Cobalt: for strength and color

    USGS Publications Warehouse

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  12. Splitting water with cobalt.

    PubMed

    Artero, Vincent; Chavarot-Kerlidou, Murielle; Fontecave, Marc

    2011-08-01

    The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable, and efficient systems for the conversion and storage of renewable energy sources, such as solar energy. The production of hydrogen, a fuel with remarkable properties, through sunlight-driven water splitting appears to be a promising and appealing solution. While the active sites of enzymes involved in the overall water-splitting process in natural systems, namely hydrogenases and photosystem II, use iron, nickel, and manganese ions, cobalt has emerged in the past five years as the most versatile non-noble metal for the development of synthetic H(2)- and O(2)-evolving catalysts. Such catalysts can be further coupled with photosensitizers to generate photocatalytic systems for light-induced hydrogen evolution from water.

  13. Macro- and microscopic properties of strontium doped indium oxide

    NASA Astrophysics Data System (ADS)

    Nikolaenko, Y. M.; Kuzovlev, Y. E.; Medvedev, Y. V.; Mezin, N. I.; Fasel, C.; Gurlo, A.; Schlicker, L.; Bayer, T. J. M.; Genenko, Y. A.

    2014-07-01

    Solid state synthesis and physical mechanisms of electrical conductivity variation in polycrystalline, strontium doped indium oxide In2O3:(SrO)x were investigated for materials with different doping levels at different temperatures (T = 20-300 °C) and ambient atmosphere content including humidity and low pressure. Gas sensing ability of these compounds as well as the sample resistance appeared to increase by 4 and 8 orders of the magnitude, respectively, with the doping level increase from zero up to x = 10%. The conductance variation due to doping is explained by two mechanisms: acceptor-like electrical activity of Sr as a point defect and appearance of an additional phase of SrIn2O4. An unusual property of high level (x = 10%) doped samples is a possibility of extraordinarily large and fast oxygen exchange with ambient atmosphere at not very high temperatures (100-200 °C). This peculiarity is explained by friable structure of crystallite surface. Friable structure provides relatively fast transition of samples from high to low resistive state at the expense of high conductance of the near surface layer of the grains. Microscopic study of the electro-diffusion process at the surface of oxygen deficient samples allowed estimation of the diffusion coefficient of oxygen vacancies in the friable surface layer at room temperature as 3 × 10-13 cm2/s, which is by one order of the magnitude smaller than that known for amorphous indium oxide films.

  14. Strain control of oxygen vacancies in epitaxial strontium cobaltite films

    SciTech Connect

    Jeen, Hyoung Jeen; Choi, Woo Seok; Reboredo, Fernando A.; Freeland, John W.; Eres, Gyula; Lee, Ho Nyung; Petrie, Jonathan R.; Mitra, Chandrima; Meyer, Tricia L.

    2016-01-25

    In this study, the ability to manipulate oxygen anion defects rather than metal cations in complex oxides can facilitate creating new functionalities critical for emerging energy and device technologies. However, the difficulty in activating oxygen at reduced temperatures hinders the deliberate control of important defects, oxygen vacancies. Here, strontium cobaltite (SrCoOx) is used to demonstrate that epitaxial strain is a powerful tool for manipulating the oxygen vacancy concentration even under highly oxidizing environments and at annealing temperatures as low as 300 °C. By applying a small biaxial tensile strain (2%), the oxygen activation energy barrier decreases by ≈30%, resulting in a tunable oxygen deficient steady-state under conditions that would normally fully oxidize unstrained cobaltite. These strain-induced changes in oxygen stoichiometry drive the cobaltite from a ferromagnetic metal towards an antiferromagnetic insulator. The ability to decouple the oxygen vacancy concentration from its typical dependence on the operational environment is useful for effectively designing oxides materials with a specific oxygen stoichiometry.

  15. Strain control of oxygen vacancies in epitaxial strontium cobaltite films

    DOE PAGES

    Jeen, Hyoung Jeen; Choi, Woo Seok; Reboredo, Fernando A.; ...

    2016-01-25

    In this study, the ability to manipulate oxygen anion defects rather than metal cations in complex oxides can facilitate creating new functionalities critical for emerging energy and device technologies. However, the difficulty in activating oxygen at reduced temperatures hinders the deliberate control of important defects, oxygen vacancies. Here, strontium cobaltite (SrCoOx) is used to demonstrate that epitaxial strain is a powerful tool for manipulating the oxygen vacancy concentration even under highly oxidizing environments and at annealing temperatures as low as 300 °C. By applying a small biaxial tensile strain (2%), the oxygen activation energy barrier decreases by ≈30%, resulting inmore » a tunable oxygen deficient steady-state under conditions that would normally fully oxidize unstrained cobaltite. These strain-induced changes in oxygen stoichiometry drive the cobaltite from a ferromagnetic metal towards an antiferromagnetic insulator. The ability to decouple the oxygen vacancy concentration from its typical dependence on the operational environment is useful for effectively designing oxides materials with a specific oxygen stoichiometry.« less

  16. 25-Hydroxyvitamin D level does not reflect intestinal calcium absorption: an assay using strontium as a surrogate marker.

    PubMed

    Camargo, Marília Brasilio Rodrigues; Vilaça, Tatiane; Hayashi, Lilian Fukusima; Rocha, Olguita G Ferreira; Lazaretti-Castro, Marise

    2015-05-01

    There is conflicting evidence as to the optimal serum 25-hydroxyvitamin D [25(OH)D] concentration for intestinal calcium absorption (Abs-Ca). Our purpose was to assess the relationship between vitamin D status and Abs-Ca in postmenopausal women. Fifty volunteers with low bone mass were grouped according to their serum 25(OH)D concentration as follows: mild deficient, <50 nmol/L (DEF) and sufficient, ≥75 nmol/L (SUF). The subjects were submitted to an oral strontium overload test to assess their Abs-Ca. Fasting blood samples were obtained to perform the relevant hormonal and biochemical tests. After the subjects received the test solution, blood samples were drawn at 30, 60, 120, and 240 min to determine the strontium concentrations. Abs-Ca was indirectly expressed as the area under the serum strontium concentration curve (AUC). A repeated measures ANOVA was performed to determine the differences among the groups. Pearson's correlation and multiple linear regression analysis were used to study the associations between the variables. The mean 25(OH)D and 1,25-dihydroxyvitamin D [1,25(OH)2D] concentrations differed between the groups (SUF vs. DEF) as follows: 98.7 ± 18.2 vs. 38.4 ± 8.5 nmol/L (p < 0.001) and 36.2 ± 10.2 vs. 24.9 ± 4.6 pg/mL (p < 0.001), respectively. There was no statistically significant difference between the groups for parathyroid hormone and AUC. Only 1,25(OH)2D influenced the strontium absorption in the last 2 h of the test. In the studied population, no correlation between levels of 25(OH)D and Abs-Ca was found. Only 1,25(OH)2D influenced Abs-Ca as measured by a strontium absorption test.

  17. Age and gender specific biokinetic model for strontium in humans

    SciTech Connect

    Shagina, N. B.; Tolstykh, E. I.; Degteva, M. O.; Anspaugh, L. R.; Napier, Bruce A.

    2015-03-01

    A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitation for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on 90Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has similar structure as the ICRP model for the alkaline earth elements. The following parameters were mainly reevaluated: gastro-intestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0–80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general population exposed to ingested strontium radioisotopes.

  18. Probing fundamental aspects of synaptic transmission with strontium.

    PubMed

    Xu-Friedman, M A; Regehr, W G

    2000-06-15

    Strontium is capable of supporting synaptic transmission, but release is dramatically different from that evoked in calcium. By measuring presynaptic strontium levels, we gain insight into the actions of strontium, which has implications for the identification of molecules involved in different aspects of synaptic transmission. We examined presynaptic divalent levels and synaptic release at the granule cell to stellate cell synapse in mouse cerebellar slices. We find that the prolonged duration of release and paired-pulse facilitation in the presence of strontium can be accounted for by the slower removal of strontium from the presynaptic terminal. Phasic and delayed release are both driven by strontium less effectively than by calcium, indicating that a heightened sensitivity to strontium is not a feature of the binding sites involved in facilitation and delayed release. We also find that the cooperativity for phasic release is 1.7 for strontium compared with 3.2 for calcium, suggesting that differential binding may help to identify the calcium sensor involved in phasic release.

  19. Strontium ranelate in postmenopausal osteoporosis treatment: a critical appraisal

    PubMed Central

    Cesareo, Roberto; Napolitano, Clemente; Iozzino, Mario

    2010-01-01

    Osteoporosis is a progressive and debilitating disease characterized by a massive bone loss with a deterioration of bone tissues, and a propensity for a fragility fracture. Strontium ranelate is the first antiosteoporotic treatment that has dual mode of action and simultaneously increases bone formation, while decreasing bone resorption, thus rebalancing bone turnover formation. Strontium ranelate rebalances bone turnover in favor of improved bone geometry, cortical thickness, trabecular bone morphology and intrinsic bone tissue quality, which translates into enhanced bone strength. This review describes the mechanism of the strontium ranelate action and its effects on bone mineral density, bone turnover, and osteoporotic fractures. The efficacy of strontium ranelate in postmenopausal osteoporosis treatment to reduce the risk of vertebral and hip fractures has been highlighted in several randomized, controlled trials. Treatment efficacy with strontium ranelate has been documented across a wide range of patient profiles: age, number of prevalent vertebral fractures, body mass index, and a family history of osteoporosis. Because strontium ranelate has a large spectrum of efficacy, it can be used to treat different subgroups of patients with postmenopausal osteoporosis. Strontium ranelate was shown to be relatively well tolerated and the safety aspects were good. Strontium ranelate should be considered as a first-line treatment for postmenopausal osteoporotic patients. PMID:21072291

  20. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    EPA Science Inventory

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  1. Age and gender specific biokinetic model for strontium in humans.

    PubMed

    Shagina, N B; Tolstykh, E I; Degteva, M O; Anspaugh, L R; Napier, B A

    2015-03-01

    A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitations for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on (90)Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has a similar structure to the ICRP model for the alkaline earth elements. The following parameters were mainly re-evaluated: gastrointestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0-80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general populations exposed to ingested strontium radioisotopes.

  2. The effects of strontium on skeletal development in zebrafish embryo.

    PubMed

    Pasqualetti, Sara; Banfi, Giuseppe; Mariotti, Massimo

    2013-10-01

    The strontium is an alkaline earth metal found in nature as trace element. Chemically similar to calcium, it is known to be involved in the human bone mineral metabolism. The strontium ranelate has been approved in therapy as drug with both anti-resorption and anabolic effects on bone tissues. Since few data in vivo are available, we used Danio rerio as animal model to evaluate the effects of strontium on skeletal development. First, toxicity assay performed on zebrafish embryos estimated the LC50 around 6mM. Since several zebrafish bones are formed from cartilage mineralization, we evaluated whether strontium affects cartilage development during embryogenesis. Strontium does not perturb the development of the cartilage tissues before the endochondral osteogenesis takes place. About the mineralization process, we evidentiated an increase of vertebral mineralization respect to controls at lower strontium concentrations whereas higher concentration inhibited mineral deposition in dose dependent fashion. Our results evidentiated, in addition, that the calcium/strontium rate but not the absolute level of strontium modulates the mineralization process during embryonic osteogenesis. Zebrafish represents an excellent animal model to study the role of micronutrients in the development of the tissues/organs because the ions are not absorbed by intestine but assumed by skin diffusion.

  3. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-06

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid. 4 figs.

  4. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid.

  5. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    EPA Science Inventory

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  6. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1993-01-01

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid.

  7. The effects of Acidithiobacillus ferrooxidans on the leaching of cobalt and strontium adsorbed onto soil particles.

    PubMed

    Park, Hyun-Sung; Lee, Jong-Un; Ahn, Jae-Woo

    2007-08-01

    Bioleaching from soil artificially contaminated with analogues of radionuclides, Co and Sr, was carried out using a Fe-oxidizing bacterium, Acidithiobacillus ferrooxidans. Due to bacterial metabolism, the pH and dissolved Fe(3+) concentration in a biotic slurry decreased and increased respectively, over time, but the concentrations of Co and Sr extracted from the soil showed no significant enhancement compared with those under abiotic control. In both cases, Co and Sr were leached from the soil during the initial period of the experiment, due to the initially low solution pH of 2.0, and the dissolved concentrations remained almost constant for the duration of the experiment (300 h). Since oxidation of Fe(2+) by A. ferrooxidans led to the production of Fe precipitates and colloidal suspensions, the Co and Sr extracted into solution were most likely re-adsorbed onto the Fe solids. Also, A. ferrooxidans, without an external supply of Fe(2+), extracted almost equal or greater amounts of Co and Sr from the soil than when Fe(2+) was supplied. Under the same leaching conditions, the extent of Sr removal was much lower than that of Co. On the contrary to the high efficiency of microbial metal leaching in biohydrometallurgy for low-graded sulfide ores, which has been widely documented, conventional bioleaching techniques with A. ferrooxidans supplied with enough Fe(2+) showed low efficiency for the removal of radionuclides loosely bound onto soil particle surfaces.

  8. Synthesis and physicochemical characterization of nanocrystalline cobalt doped lanthanum strontium ferrite

    NASA Astrophysics Data System (ADS)

    Nityanand, Chaubey; Nalin, Wani Bina; Rajkumar, Bharadwaj Shyamala; Chandra, Chattopadhyaya Mahesh

    2011-05-01

    Nanosized crystallites of La 0.6Sr 0.4Fe 0.8Co 0.2O 3- δ (LSCF), a promising cathode material for Intermediate Temperature-Solid Oxide Fuel Cells (IT-SOFCs) has been synthesized by alternative methods like ceramic route, polymerisable complex process and gel-combustion method and calcined at different temperatures. X-ray diffraction studies were used for the determination of phase purity, crystal structure and average crystallite size of the samples. Microstructure of LSCF samples was studied by SEM. Temperature-programmed reduction studies were done for evaluating the redox behavior of the samples prepared by alternative methods. The electrical conductivity measurements of sintered samples were carried out at elevated temperatures using four-probe method. The electrical conductivity of sample synthesized by gel-combustion method was more as compared to sample prepared by polymerisable complex process and ceramic route. The electrical conductivity decreased at high temperature due to loss of oxygen and the formation of oxygen vacancies. Thermo-dilatometry was used to study the linear thermal expansion behavior of the samples which shows that there is an observable increase in thermal expansion at high temperatures.

  9. Topotactic synthesis of strontium cobalt oxyhydride thin film with perovskite structure

    SciTech Connect

    Katayama, Tsukasa; Chikamatsu, Akira Kamisaka, Hideyuki; Yokoyama, Yuichi; Hirata, Yasuyuki; Wadati, Hiroki; Fukumura, Tomoteru; Hasegawa, Tetsuya

    2015-10-15

    The substitution of hydride anions (H{sup −}) into transition metal oxides has recently become possible through topotactic reactions or high-pressure synthesis methods. However, the fabrication of oxyhydrides is still difficult because of their inherently less-stable frameworks. In this study, we successfully fabricated perovskite SrCoO{sub x}H{sub y} thin films via the topotactic hydride doping of brownmillerite SrCoO{sub 2.5} epitaxial thin films with CaH{sub 2}. The perovskite-type cation framework was maintained during the topotactic treatment owing to epitaxial stabilization. Structural and chemical analyses accompanied by X-ray absorption spectroscopy measurements revealed that the doped hydride ions form a two-dimensional network of Co-H{sup −}-Co bonds, in contrast to other reported perovskite oxyhydrides, SrMO{sub 3−x}H{sub x} (M = Cr, Ti, V). The SrCoO{sub x}H{sub y} thin film exhibited insulating behavior and had a direct band gap of 2.1 eV. Thus, topotactic hydride doping of transition-metal-oxide thin films on suitable substrates is a promising method for the synthesis of new transition metal oxyhydrides.

  10. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... concentrations. 35.204 Section 35.204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL..., and strontium-85 concentrations. (a) A licensee may not administer to humans a radiopharmaceutical... radiopharmaceutical shall measure the molybdenum-99 concentration of the first eluate after receipt of a generator to...

  11. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... concentrations. 35.204 Section 35.204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL..., and strontium-85 concentrations. (a) A licensee may not administer to humans a radiopharmaceutical... radiopharmaceutical shall measure the molybdenum-99 concentration of the first eluate after receipt of a generator to...

  12. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... concentrations. 35.204 Section 35.204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL..., and strontium-85 concentrations. (a) A licensee may not administer to humans a radiopharmaceutical... radiopharmaceutical shall measure the molybdenum-99 concentration of the first eluate after receipt of a generator to...

  13. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... concentrations. 35.204 Section 35.204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL..., and strontium-85 concentrations. (a) A licensee may not administer to humans a radiopharmaceutical... radiopharmaceutical shall measure the molybdenum-99 concentration of the first eluate after receipt of a generator to...

  14. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... concentrations. 35.204 Section 35.204 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL..., and strontium-85 concentrations. (a) A licensee may not administer to humans a radiopharmaceutical... radiopharmaceutical shall measure the molybdenum-99 concentration of the first eluate after receipt of a generator to...

  15. Laser Ablation Molecular Isotopic Spectrometry: Strontium and its isotopes

    NASA Astrophysics Data System (ADS)

    Mao, Xianglei; Bol'shakov, Alexander A.; Choi, Inhee; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman; Russo, Richard E.

    2011-11-01

    The experimental details are reported of Laser Ablation Molecular Isotopic Spectrometry (LAMIS) and its application for performing optical isotopic analysis of solid strontium-containing samples in ambient atmospheric air at normal pressure. The LAMIS detection method is described for strontium isotopes from samples of various chemical and isotopic compositions. The results demonstrate spectrally resolved measurements of the three individual 86Sr, 87Sr, and 88Sr isotopes that are quantified using multivariate calibration of spectra. The observed isotopic shifts are consistent with those calculated theoretically. The measured spectra of diatomic oxide and halides of strontium generated in laser ablation plasmas demonstrate the isotopic resolution and capability of LAMIS. In particular, emission spectra of SrO and SrF molecular radicals provided clean and well resolved spectral signatures for the naturally occurring strontium isotopes. A possibility is discussed of using LAMIS of strontium isotopes for radiogenic age determination.

  16. Measurement of Strontium Monoxide in Methane-Air Flames.

    PubMed

    Wimberly, Bobby J; Hornkohl, James O; Parigger, Christian G

    2017-02-01

    The spectroscopy of alkaline earth metal compounds is stimulated by the use of these compounds in practical areas ranging from technology to medicine. Applications in the field of pyrotechnics were the motivation for a series of flame emission spectroscopy experiments with strontium-containing compounds. Specifically, strontium monoxide (SrO) was studied as a candidate radiator for the diagnosis of methane-air flames. Strontium monoxide emissions have been observed in flames with temperatures in the range 1200 K to 1600 K for two compounds: strontium hydroxide and strontium chloride. Comparisons are made of the measured SrO spectra to simulated spectra in the near-infrared region of 700 nm to 900 nm.

  17. Strontium Promotes Cementoblasts Differentiation through Inhibiting Sclerostin Expression In Vitro

    PubMed Central

    Bao, Xingfu; Liu, Xianjun; Zhang, Yi; Cui, Yue; Yao, Jindan

    2014-01-01

    Cementogenesis, performed by cementoblasts, is important for the repair of root resorption caused by orthodontic treatment. Based on recent studies, strontium has been applied for osteoporosis treatment due to its positive effect on osteoblasts. Although promising, the effect of strontium on cementoblasts is still unclear. So the aim of this research was to clarify and investigate the effect of strontium on cementogenesis via employing cementoblasts as model. A series of experiments including MTT, alkaline phosphatase activity, gene analysis, alizarin red staining, and western blot were carried out to evaluate the proliferation and differentiation of cementoblasts. In addition, expression of sclerostin was checked to analyze the possible mechanism. Our results show that strontium inhibits the proliferation of cementoblasts with a dose dependent manner; however, it can promote the differentiation of cementoblasts via downregulating sclerostin expression. Taking together, strontium may facilitate cementogenesis and benefit the treatment of root resorption at a low dose. PMID:25003114

  18. Strontium promotes cementoblasts differentiation through inhibiting sclerostin expression in vitro.

    PubMed

    Bao, Xingfu; Liu, Xianjun; Zhang, Yi; Cui, Yue; Yao, Jindan; Hu, Min

    2014-01-01

    Cementogenesis, performed by cementoblasts, is important for the repair of root resorption caused by orthodontic treatment. Based on recent studies, strontium has been applied for osteoporosis treatment due to its positive effect on osteoblasts. Although promising, the effect of strontium on cementoblasts is still unclear. So the aim of this research was to clarify and investigate the effect of strontium on cementogenesis via employing cementoblasts as model. A series of experiments including MTT, alkaline phosphatase activity, gene analysis, alizarin red staining, and western blot were carried out to evaluate the proliferation and differentiation of cementoblasts. In addition, expression of sclerostin was checked to analyze the possible mechanism. Our results show that strontium inhibits the proliferation of cementoblasts with a dose dependent manner; however, it can promote the differentiation of cementoblasts via downregulating sclerostin expression. Taking together, strontium may facilitate cementogenesis and benefit the treatment of root resorption at a low dose.

  19. Calcium versus strontium handling by the heart muscle.

    PubMed

    Hendrych, Michal; Olejnickova, Veronika; Novakova, Marie

    2016-01-01

    Calcium plays a crucial role in numerous processes in living systems, from both intracellular and intercellular signalling to blood clotting. Calcium can be replaced by strontium in various intracellular processes due to high level of their similarity and strontium thus may serve as a valuable tool for different experimental studies. On the other hand, strontium is also used in clinical medicine and is commonly taken to the human body with food and water. The negative cardiac side effects of strontium therapy of osteoporosis and bone metastases are well known, but still not fully explained. This fact explains enhanced interest in this element and its impact on human body. This article reviews effects of calcium and strontium on several biochemical and physiological processes, with special emphasis on cardiac muscle.

  20. Wrought cobalt-base superalloys

    SciTech Connect

    Klarstrom, D.L. )

    1993-08-01

    Wrought cobalt-base superalloys are used extensively in gas turbine engines because of their excellent high-temperature creep and fatigue strength and resistance to hot corrosion attach. In addition, the unique character of the oxide scales that form on some of the alloys provides outstanding resistance to high-temperature sliding wear. This article provides a review of the evolutionary development of wrought cobalt-base alloys in terms of alloy design and physical metallurgy. The topics include solid-solution strengthening, carbide precipitation characteristics, and attempts to introduce age hardening. The use of PHACOMP to enhance thermal stability characteristics and the incorporation of rare-earth elements to improve oxidation resistance is also reviewed and discussed. The further development of cobalt-base superalloys has been severely hampered by past political events, which have accentuated the strategic vulnerability of cobalt as a base or as an alloying element. Consequently, alternative alloys have been developed that use little or no cobalt. One such alternative, Haynes 230 alloy, is discussed briefly.

  1. Crystalline silicotitanates for cesium/strontium removal

    SciTech Connect

    Brown, N.; Miller, J.; Sherman, J.

    1996-10-01

    A new class of inorganic ion exchangers called crystalline silicotitanates (CST) has been developed that exhibits very high selectivity for cesium and strontium in the highly alkaline radioactive wastes at the Hanford Site and other DOE sites. Tests have also shown that CSTs have high selectivity for cesium in acidic and neutral solutions. The ESP is supporting an effort at Sandia National Laboratories and Texas A & M University to further develop and characterize the important chemical and physical properties that will determine the applicability of CST to radioactive waste treatment at Hanford and other DOE facilities.

  2. Anisotropic thermal expansion of strontium barium niobate

    NASA Astrophysics Data System (ADS)

    Qadri, Syed B.; Bellotti, Jeffrey A.; Garzarella, Anthony; Wu, Dong Ho

    2005-06-01

    Strontium barium niobate is a tungsten-bronze ferroelectric crystal having a tetragonal unit cell. Low-temperature x-ray diffraction studies were performed on a single crystal of Sr0.75Ba0.25Nb2O6 to determine the thermal expansivity along the a- and c-axes. Negative thermal expansion was observed along the c direction while a positive thermal expansion was measured along the a axis. The anisotropic thermal expansion behavior is explained as arising due to the geometry of the crystal structure.

  3. Nondestructive measurement of environmental radioactive strontium

    NASA Astrophysics Data System (ADS)

    Saiba, Shuntaro; Okamiya, Tomohiro; Tanaka, Saki; Tanuma, Ryosuke; Totsuka, Yumi; Murata, Jiro

    2014-03-01

    The Fukushima Daiichi nuclear power plant accident was triggered by the 2011 Great East Japan Earthquake. The main radioactivity concerns after the accident are I-131 (half-life: 8.0 days), Cs-134 (2.1 years), Cs-137 (30 years), Sr-89 (51 days), and Sr-90 (29 years). We are aiming to establish a new nondestructive measurement and detection technique that will enable us to realize a quantitative evaluation of strontium radioactivity without chemical separation processing. This technique is needed to detect radiation contained in foods, environmental water, and soil, to prevent us from undesired internal exposure to radiation.

  4. Efficient cooling and trapping of strontium atoms.

    PubMed

    Courtillot, I; Quessada, A; Kovacich, R P; Zondy, J J; Landragin, A; Clairon, A; Lemonde, P

    2003-03-15

    We report the capture of cold strontium atoms in a magneto-optical trap (MOT) at a rate of 4 x 10(10) atoms/s. The MOT is loaded from an atomic beam decelerated by a Zeeman slower operating with a focused laser beam. The 461-nm laser, used for both cooling and trapping, was generated by sum-frequency mixing in a KTP crystal with diode lasers at 813 nm and a Nd:YAG laser at 1064 nm. As much as 115 mW of blue light was obtained.

  5. Strontium-90 and promethium-147 recovery

    SciTech Connect

    Hoisington, J.E.; McDonell, W.R.

    1982-08-30

    Strontium-90 and promethium-147 are fission product radionuclides with potential for use as heat source materials in high reliability, non-interruptible power supplies. Interest has recently been expressed in their utilization for Department of Defense (DOD) applications. This memorandum summarizes the current inventories, the annual production rates, and the possible recovery of Sr-90 and Pm-147 from nuclear materials production operations at Hanford and Savannah River. Recovery of these isotopes from LWR spend fuel utilizing the Barnwell Nuclear Fuels Plant (BNFP) is also considered. Unit recovery costs at each site are provided.

  6. Cobalt-60 production at Savannah River

    SciTech Connect

    Allen, H.F.

    1995-02-01

    Over the past 8 or 9 years, the Savannah River Plant (SRP) has produced close to 4 million curies of cobalt-60 by irradiating cobalt-59 in the production reactors. This paper reviews past and current irradiations, cobalt-60 production methods, and costs.

  7. Transport of cobalt-60 industrial radiation sources

    NASA Astrophysics Data System (ADS)

    Kunstadt, Peter; Gibson, Wayne

    This paper will deal with safety aspects of the handling of Cobalt-60, the most widely used industrial radio-isotope. Cobalt-60 is a man-made radioisotope of Cobalt-59, a naturally occurring non radioactive element, that is made to order for radiation therapy and a wide range of industrial processing applications including sterilization of medical disposables, food irradiation, etc.

  8. Investigation of strontium accumulation on ovariectomized Sprague-Dawley rat tibia by micro-PIXE

    NASA Astrophysics Data System (ADS)

    Li, X.; Li, Y.; Jin, W.; Zheng, Y.; Rong, C.; Lyu, H.; Shen, H.

    2014-08-01

    Strontium ranelate is a newly developed drug effective in osteoporosis treatment by depressing bone resorption and maintaining bone formation. Strontium accumulation and distribution are determined in bones of rat after strontium ranelate administration by using micro-PIXE. The investigated rats are divided into four groups: (A) control, (B) ovariectomized, (C) ovariectomized followed with strontium chloride, (D) ovariectomized followed with strontium ranelate. It was found that strontium ranelate would result in increasing trabecular volume and decreasing bone resorption to treat osteoporosis. There are similar contours of calcium and strontium in two-dimensional images, while the strontium is not evenly distributed in the bone. It supports the conclusion that strontium has an affinity for bone and it is capable of replacing calcium atoms as a part of the strontium mechanism in the osteoporosis treatment. The results related to biochemistry are also discussed.

  9. Immunization against strontium-90 induction of bone tumors with inactivated FBJ virus and irradiated syngeneic strontium-90-induced tumor cells

    SciTech Connect

    Reif, A.E.; Triest, W.E.

    1981-01-01

    Three hundred six C57BL/6J female mice were subdivided into a control group left untreated and an experimental group treated intraperitoneally with 1.0 ..mu..Ci strontium-90/g of body weight at an age of 66 days. Treatments for the groups were as follows: none, 6 injections of formalin-inactivated FBJ viral preparation, 6 injections of active FBJ viral preparation, and 2 injections of 10,000 rad irradiated transplantable osteosarcoma previously induced in C57BL/6J mice by strontium-90. In addition to the above groups, two other groups were treated with respectively 0.032 and 0.10 ..mu..Ci strontium-90/g body weight in order to obtain information on the dose-response relationship between the injection of strontium-90 and the yield of bone tumors. In the groups not treated with strontium-90, only 1 bone tumor developed; this occurred in the group injected with FBJ virus. The incidence of bone tumors in the groups treated with 1.0 ..mu..Ci strontium-90 was significantly lower (18.5% or 18.2%) in the two groups that had received injections of inactivated FBJ virus or irradiated isogenic osteosarcoma when compared to the group left uninjected, which developed 43.5% tumors. In contrast, the strontium-90-treated group that also received injections of active FBJ virus developed 63.0% tumors. Only a single bone tumor developed in the groups treated solely with intermediate doses of strontium-90. The results indicate that immunization with inactivated FBJ virus or with irradiated syngeneic strontium-90-induced tumor cells can significantly decrease the development of strontium-90-induced tumors.

  10. Extraction processes and solvents for recovery of cesium, strontium, rare earth elements, technetium and actinides from liquid radioactive waste

    DOEpatents

    Zaitsev, Boris N.; Esimantovskiy, Vyacheslav M.; Lazarev, Leonard N.; Dzekun, Evgeniy G.; Romanovskiy, Valeriy N.; Todd, Terry A.; Brewer, Ken N.; Herbst, Ronald S.; Law, Jack D.

    2001-01-01

    Cesium and strontium are extracted from aqueous acidic radioactive waste containing rare earth elements, technetium and actinides, by contacting the waste with a composition of a complex organoboron compound and polyethylene glycol in an organofluorine diluent mixture. In a preferred embodiment the complex organoboron compound is chlorinated cobalt dicarbollide, the polyethylene glycol has the formula RC.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.n OH, and the organofluorine diluent is a mixture of bis-tetrafluoropropyl ether of diethylene glycol with at least one of bis-tetrafluoropropyl ether of ethylene glycol and bis-tetrafluoropropyl formal. The rare earths, technetium and the actinides (especially uranium, plutonium and americium), are extracted from the aqueous phase using a phosphine oxide in a hydrocarbon diluent, and reextracted from the resulting organic phase into an aqueous phase by using a suitable strip reagent.

  11. Controlling the misuse of cobalt in horses.

    PubMed

    Ho, Emmie N M; Chan, George H M; Wan, Terence S M; Curl, Peter; Riggs, Christopher M; Hurley, Michael J; Sykes, David

    2015-01-01

    Cobalt is a well-established inducer of hypoxia-like responses, which can cause gene modulation at the hypoxia inducible factor pathway to induce erythropoietin transcription. Cobalt salts are orally active, inexpensive, and easily accessible. It is an attractive blood doping agent for enhancing aerobic performance. Indeed, recent intelligence and investigations have confirmed cobalt was being abused in equine sports. In this paper, population surveys of total cobalt in raceday samples were conducted using inductively coupled plasma mass spectrometry (ICP-MS). Urinary threshold of 75 ng/mL and plasma threshold of 2 ng/mL could be proposed for the control of cobalt misuse in raceday or in-competition samples. Results from administration trials with cobalt-containing supplements showed that common supplements could elevate urinary and plasma cobalt levels above the proposed thresholds within 24 h of administration. It would therefore be necessary to ban the use of cobalt-containing supplements on raceday as well as on the day before racing in order to implement and enforce the proposed thresholds. Since the abuse with huge quantities of cobalt salts can be done during training while the use of legitimate cobalt-containing supplements are also allowed, different urinary and plasma cobalt thresholds would be required to control cobalt abuse in non-raceday or out-of-competition samples. This could be achieved by setting the thresholds above the maximum urinary and plasma cobalt concentrations observed or anticipated from the normal use of legitimate cobalt-containing supplements. Urinary threshold of 2000 ng/mL and plasma threshold of 10 ng/mL were thus proposed for the control of cobalt abuse in non-raceday or out-of-competition samples. Copyright © 2014 John Wiley & Sons, Ltd.

  12. Cobalt Alums. A Demonstration Experiment

    NASA Astrophysics Data System (ADS)

    Schäffer, Claus E.; Steenberg, Paul

    2002-08-01

    The demonstration experiment describes the isolation of [Co(H2O)6]3+ both as the pure blue crystalline cesium cobalt alum, CsCo(SO4)2·12H2O, and as a light greenish-blue solid solution of ammonium cobalt alum in (NH4)Al(SO4)2·12H2O. The hexaaquacobalt(III) ion is prepared chemically by oxidation with hydrogen peroxide, taking advantage of the stabilization of CoIII relative to CoII by complexation with the carbonate ligand. A brief description of alum structure and a characterization of alum subclasses are included.

  13. Cobalt Excretion Test for the Assessment of Body Iron Stores

    PubMed Central

    Sorbie, Janet; Olatunbosun, David; Corbett, William E. N.; Valberg, Leslie S.

    1971-01-01

    Iron absorption is under delicate control and the level of absorption is adjusted to comply with the body's need for iron. To measure the intestinal setting for iron absorption, and thereby indirectly assess body iron requirements, cobaltous chloride labelled with 57Co or 60Co was given by mouth and the percentage of the test dose excreted in the urine in 24 hours was measured in a gamma counter. Seventeen control subjects with normal iron stores excreted 18% (9-23%) of the dose. Increased excretion, 31% (23-42%), was found in 10 patients with iron deficiency anemia and in 15 patients with depleted iron stores in the absence of anemia. In contrast, 12 patients with anemia due to causes other than iron deficiency excreted amounts of radiocobalt within the normal control range. In patients with iron deficiency, replenishment of iron stores by either oral or parenteral iron caused the previously high results to return to normal. Excretion of the test dose was normal in portal cirrhosis with normal iron stores but it was markedly increased in patients with cirrhosis complicated by either iron deficiency or endogenous iron overload. It was also raised in primary hemochromatosis. Excretion of the dose was reduced in gluten-sensitive enteropathy. Gastrointestinal surgery and inflammatory disease of the lower small intestine had no effect on the results except that some patients with steatorrhea had diminished excretion. The cobalt excretion test provides the clinician with a tool for the assessment of iron absorption, the detection of a reduction in body iron stores below the level that is normal for the subject in question, the differentiation of iron deficiency anemia from anemia due to other causes, and the investigation of patients with iron-loading disorders. PMID:5578125

  14. Structural investigations of lead-strontium fluoroapatites

    SciTech Connect

    Badraoui, Bechir; Aissa, Abdallah; Bigi, Adriana; Debbabi, Mongi; Gazzano, Massimo . E-mail: gazzano@isof.cnr.it

    2006-10-15

    Solid solutions in the system Pb{sub (10-x)}Sr {sub x} (PO{sub 4}){sub 6}F{sub 2}, 0{<=}x{<=}10, were obtained as apatitic phases from aqueous medium. They were investigated by X-ray diffraction, chemical analysis and infrared (IR) spectroscopy. The results of the structural refinements indicated that the substitution of lead by strontium induces a regular decrease of the lattice constant 'a' and a preferential strontium distribution in site M(1). A progressive shift of the F{sup -} ion position along the apatitic channel was detected and confirmed by IR evidence. The different character of the M-F and M-O interactions was invoked to justify the structural differences observed as a function of composition. - Graphical abstract: The structural refinements carried out on five Pb{sub (10-x)}Sr {sub x} (PO{sub 4}){sub 6}F{sub 2} samples evidence preferential distribution of cations in metal sites and a progressive shift of the F{sup -} ion.

  15. Simple test of intestinal calcium absorption measured by stable strontium.

    PubMed Central

    Milsom, S; Ibbertson, K; Hannan, S; Shaw, D; Pybus, J

    1987-01-01

    A clinical test of intestinal calcium absorption has been developed using non-radioactive stable strontium as a calcium tracer. In nine elderly subjects there was a close correlation between the fractional absorption of strontium and radioactive calcium (45Ca) during a five hour period after the simultaneous oral administration of the two tracers. Comparable precision was achieved with each tracer in six subjects in whom the test was repeated after two weeks. The effect of food on strontium absorption was examined in a further 33 normal subjects (age 21-60 years), and the administration of the strontium with a standard breakfast was shown to reduce the variance at individual time points. A simplified test in which serum strontium concentration was measured four hours after the oral dose given with a standard breakfast was adopted as the routine procedure. The normal range (mean (2 SD], established over 97 tests in 53 patients, was 7.0-18.0% of the dose in the extracellular fluid. A further 30 patients with possible disorders of calcium absorption (10 with primary hyperparathyroidism and 20 with coeliac disease) were studied by this standard test. In both groups of patients the mean four hour strontium values were significantly different from normal. This standard strontium absorption test allows assessment of calcium absorption with sufficient sensitivity and precision to have a wide application in clinical practice. PMID:3115389

  16. Effect of Strontium Chloride on Experimental Bladder Inflammation in Rat

    PubMed Central

    Coskun, Kubra Acikalin; Akyol, Melih; Tutar, Yusuf; Ayan, Semih; Gokce, Gokhan; Gultekin, Emin Yener

    2014-01-01

    Introduction. Strontium salts are anti-irritants for chemically induced sensory irritation. Interstitial cystitis is a painful disease without definitive therapy. The aim of the study was to determine the effect of strontium in bladder with experimental interstitial cystitis model. Material and Methods. Rats' bladders in control group were instilled with NaCl. Second group was instilled with E. coli LPS. Third group was instilled with strontium. Fourth group was initially instilled with strontium and then LPS. Fifth group was instilled with LPS initially and then strontium. Urine of rats was collected at the beginning and end of the study. Results. Histamine and TNF-α changes were statistically significant in the second group but were not significant in the third group. When we compared the histamine levels of second via fourth and fifth groups the changes were statistically not significant. When we compared the TNF-α levels of second via fourth and fifth groups the changes were statistically significant. Conclusions. In our model, strontium did not make any significant changes in histopathology or histamine levels; however, it significantly reduced the levels of TNF-α. Given the role of TNF-α in the physiopathology of interstitial cystitis, these results suggested that further studies are required to evaluate the potential use of strontium in the management of interstitial cystitis. PMID:27355060

  17. Groundwater transport of strontium 90 in a glacial outwash environment

    USGS Publications Warehouse

    Kipp, Kenneth L.; Stollenwerk, Kenneth G.; Grove, David B.

    1986-01-01

    As part of the investigation of groundwater contamination at a uranium-scrap recovery plant at Wood River Junction, Rhode Island, laboratory experiments led to the development of a model for predicting the transport of strontium 90 in glacial outwash sediments based on an approximate mechanism for ion exchange. The multicomponent system was simplified to two components by regarding all exchangeable cations other than strontium 90 as a single component. The binary ion-exchange parameter was a function of the variable, total ion concentration. A one-dimensional solute transport model was formulated to evaluate the time necessary for natural groundwater flow to remove the strontium 90 contamination plume from the groundwater system to the Pawcatuck River. The finite difference transport equations were solved sequentially for total ion concentrations, then strontium 90 concentrations. Clay-free quartz and feldspar sands at the study site have little potential for strontium 90 sorption, and high calcium, magnesium, and sodium concentrations compete for the few ion exchange sites. As the total ion concentration plume moves out of the system, ion exchange of strontium 90 increases, reducing the strontium 90 concentration in the groundwater. Cleanout times predicted using the binary ion exchange mechanism were about two thirds of those predicted using a constant distribution coefficient. It is suggested that this type of model can simulate solute transport more realistically in many groundwater systems where the total ion concentration is not constant.

  18. Groundwater Transport of Strontium 90 in a Glacial Outwash Environment

    NASA Astrophysics Data System (ADS)

    Kipp, Kenneth L., Jr.; Stollenwerk, Kenneth G.; Grove, David B.

    1986-04-01

    As part of the investigation of groundwater contamination at a uranium-scrap recovery plant at Wood River Junction, Rhode Island, laboratory experiments led to the development of a model for predicting the transport of strontium 90 in glacial outwash sediments based on an approximate mechanism for ion exchange. The multicomponent system was simplified to two components by regarding all exchangeable cations other than strontium 90 as a single component. The binary ion-exchange parameter was a function of the variable, total ion concentration. A one-dimensional solute transport model was formulated to evaluate the time necessary for natural groundwater flow to remove the strontium 90 contamination plume from the groundwater system to the Pawcatuck River. The finite difference transport equations were solved sequentially for total ion concentrations, then strontium 90 concentrations. Clay-free quartz and feldspar sands at the study site have little potential for strontium 90 sorption, and high calcium, magnesium, and sodium concentrations compete for the few ion exchange sites. As the total ion concentration plume moves out of the system, ion exchange of strontium 90 increases, reducing the strontium 90 concentration in the groundwater. Cleanout times predicted using the binary ion exchange mechanism were about two thirds of those predicted using a constant distribution coefficient. It is suggested that this type of model can simulate solute transport more realistically in many groundwater systems where the total ion concentration is not constant.

  19. Development of Cesium and Strontium Separation and Immobilization Technologies in Support of an Advanced Nuclear Fuel Cycle

    SciTech Connect

    Jack D. Law; Troy G. Garn; R. Scott Herbst; David H. Meikrantz; Dean R. Peterman; Catherine L. Riddle; Terry A. Todd; Julie L. Tripp

    2006-02-01

    As part of the Advanced Fuel Cycle Initiative, two solvent extraction technologies are being developed at the Idaho National Laboratory to simultaneously separate cesium and strontium from dissolved spent nuclear fuel. The chlorinated cobalt dicarbollide/polyethylene glycol (CCD/PEG) process utilizes a solvent consisting of chlorinated cobalt dicarbollide for the extraction of Cs and polyethylene glycol for the synergistic extraction of Sr in a phenyltrifluoromethyl sulfone diluent. Countercurrent flowsheets have been designed and tested on simulated and actual spent nuclear fuel feed streams with both cesium and strontium removal efficiencies of greater than 99%. The Fission Product Extraction (FPEX) process is based on two highly-specific extractants: 4,4',(5')-Di-(t-butyldicyclo-hexano)-18-crown-6 (DtBuCH18C6) for the extraction of Sr and Calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6) for the extraction of Cs. Laboratory test results of the FPEX process, using simulated feed solution spiked with radiotracers, indicate good Cs and Sr extraction and stripping performance. A preliminary solvent extraction flowsheet for the treatment of spent nuclear fuel with the FPEX process has been developed, and testing of the flowsheet with simulated spent nuclear fuel solutions is planned in the near future. Steam reforming is currently being developed for stabilization of the Cs/Sr product stream because it can produce a solid waste form while retaining the Cs and Sr in the solid, destroy the nitrates and organics present in these aqueous solutions, and convert the Cs and Sr into leach resistant aluminosilicate minerals. A bench-scale steam reforming pilot plant has been operated with several potential feed compositions and steam reformed product has been generated and analyzed.

  20. Calcium phosphate cements with strontium halides as radiopacifiers.

    PubMed

    López, Alejandro; Montazerolghaem, Maryam; Engqvist, Håkan; Ott, Marjam Karlsson; Persson, Cecilia

    2014-02-01

    High radiopacity is required to monitor the delivery and positioning of injectable implants. Inorganic nonsoluble radiopacifiers are typically used in nondegradable bone cements; however, their usefulness in resorbable cements is limited due to their low solubility. Strontium halides, except strontium fluoride, are ionic water-soluble compounds that possess potential as radiopacifiers. In this study, we compare the radiopacity, mechanical properties, composition, and cytotoxicity of radiopaque brushite cements prepared with strontium fluoride (SrF2 ), strontium chloride (SrCl2 ·6H2 O), strontium bromide (SrBr2 ), or strontium iodide (SrI2 ). Brushite cements containing 10 wt % SrCl2 ·6H2 O, SrBr2 , or SrI2 exhibited equal to or higher radiopacity than commercial radiopaque cements. Furthermore, the brushite crystal lattice in cements that contained the ionic radiopacifiers was larger than in unmodified cements and in cements that contained SrF2 , indicating strontium substitution. Despite the fact that the strontium halides increased the solubility of the cements and affected their mechanical properties, calcium phosphate cements containing SrCl2 ·6H2 O, SrBr2 , and SrI2 showed no significant differences in Saos-2 cell viability and proliferation with respect to the control. Strontium halides: SrCl2 ·6H2 O, SrBr2 , and SrI2 may be potential candidates as radiopacifiers in resorbable biomaterials although their in vivo biocompatibility, when incorporated into injectable implants, is yet to be assessed.

  1. Cobalt(II) and Cobalt(III) Coordination Compounds.

    ERIC Educational Resources Information Center

    Thomas, Nicholas C.; And Others

    1989-01-01

    Presents a laboratory experiment which illustrates the formation of tris(phenanthroline)cobalt complexes in the 2+ and 3+ oxidation states, the effect of coordination on reactions of the ligand, and the use of a ligand displacement reaction in recovering the transformed ligand. Uses IR, UV-VIS, conductivity, and NMR. (MVL)

  2. Cobalt(II) and Cobalt(III) Coordination Compounds.

    ERIC Educational Resources Information Center

    Thomas, Nicholas C.; And Others

    1989-01-01

    Presents a laboratory experiment which illustrates the formation of tris(phenanthroline)cobalt complexes in the 2+ and 3+ oxidation states, the effect of coordination on reactions of the ligand, and the use of a ligand displacement reaction in recovering the transformed ligand. Uses IR, UV-VIS, conductivity, and NMR. (MVL)

  3. Bentonite-Clay Waste Form for the Immobilization of Cesium and Strontium from Fuel Processing Waste Streams

    SciTech Connect

    Kaminski, Michael D.; Mertz, Carol J.

    2016-01-01

    The physical properties of a surrogate waste form containing cesium, strontium, rubidium, and barium sintered into bentonite clay were evaluated for several simulant feed streams: chlorinated cobalt dicarbollide/polyethylene glycol (CCD-PEG) strip solution, nitrate salt, and chloride salt feeds. We sintered bentonite clay samples with a loading of 30 mass% of cesium, strontium, rubidium, and barium to a density of approximately 3 g/cm3. Sintering temperatures of up to 1000°C did not result in volatility of cesium. Instead, there was an increase in crystallinity of the waste form upon sintering to 1000ºC for chloride- and nitrate-salt loaded clays. The nitrate salt feed produced various cesium pollucite phases, while the chloride salt feed did not produce these familiar phases. In fact, many of the x-ray diffraction peaks could not be matched to known phases. Assemblages of silicates were formed that incorporated the Sr, Rb, and Ba ions. Gas evolution during sintering to 1000°C was significant (35% weight loss for the CCD-PEG waste-loaded clay), with significant water being evolved at approximately 600°C.

  4. Metallurgical Properties and Phase Transformations of Barium-Strontium Modifier

    NASA Astrophysics Data System (ADS)

    Platonov, M. A.; Sulimova, I. S.; Rozhikhina, I. D.; Dmitrienko, V. I.; Horoshun, G. V.

    2016-04-01

    Metallurgical properties and phase transformations of barium-strontium modifier were tested in laboratory conditions resembling steel processing in furnace and ladle. When heating barium-strontium modifier start of melting, kinetics of decomposition, phase and structure transformation were studied. The concentrate under consideration has been revealed to be a complex mineral compound containing barytocalcite, calcite, calciostrontianite, dolomite and siderite. The reaction kinetics of decomposing mineral components of barium-strontium modifier to oxides does not considerably affect slag formation in conditions of out-of-furnace steel processing.

  5. Strontium ranelate: a new paradigm in the treatment of osteoporosis.

    PubMed

    Reginster, Jean-Yves; Lecart, Marie-Paule; Deroisy, Rita; Lousberg, Christian

    2004-07-01

    In vitro, strontium ranelate increases collagen and non-collagenic protein synthesis by mature osteoblast-enriched cells. The effects of strontium ranelate on bone formation were confirmed as the drug enhanced preosteoblastic cell replication. In the isolated osteoclast, a preincubation of bone slices with strontium ranelate induced a dose-dependent inhibition of the bone resorbing activity of treated rat osteoclast. Strontium ranelate dose-dependently inhibited preosteoclast differentiation. The drug was administered in 160 early postmenopausal women, in a 24-month, double-blind, placebo-controlled, prospective randomised study. At the conclusion of the study, the percentage variation of lumbar bone mineral density (BMD) from baseline was significantly different in the group receiving strontium ranelate 1000 mg/day as compared with placebo (+5.53 versus -0.75%, respectively). Increase in total hip and neck BMD averages were 3.2 and 2.5%, respectively. The effect of strontium ranelate in postmenopausal women with established osteoporosis was assessed during a multinational, prospective, double-blind, randomised, placebo-controlled trial. Strontium ranelate (500, 1000, 2000 mg/day) or placebo were given to 353 Caucasian women with prevalent vertebral osteoporosis. At the conclusion of this 2-year study, the annual increase in lumbar BMD of the group receiving strontium ranelate 2000 mg was 7.3% (p < 0.001). A significant increase in bone alkaline phophatase (p = 0.002) over a 6-month period and a significant decrease in N-telopeptide crosslinks (p = 0.004) throughout the 2-year period were seen in the group receiving 2000 mg of strontium ranelate. During the second year of treatment, the dose of 2000 mg was associated with a 44% reduction in the number of patients experiencing a new vertebral deformity. Bone histomorphometry showed no mineralisation defects. The primary analysis of the SOTI study, evaluating the effect of strontium ranelate 2000 mg on vertebral

  6. The effect of strontium non-stoichiometry on the physical properties of double perovskite Sr{sub 2}FeMoO{sub 6}

    SciTech Connect

    Harnagea, L. Berthet, P.

    2015-02-15

    We present a detailed study on the effect of strontium non-stoichiometry on the properties of double perovskite Sr{sub 2}FeMoO{sub 6} (SFMO). A citrate route has been used to prepare high quality polycrystalline samples with (2−x)Sr:Fe:Mo (x=0, 0.02, 0.04) and (2+x)Sr:Fe:Mo (x=0.02, 0.04, 0.10) cationic ratios. The strontium deficient samples exhibit a significant decrease in their values of saturation magnetization (Ms), Curie temperature (Tc) and magnetoresistance (MR) compared to the stoichiometric SFMO. On the other hand, the samples prepared with an excess of strontium, respectively those with x=0.02 and 0.04, show remarkably superior magneto–transport characteristics, despite of their increased level of Fe/Mo disorder and somewhat diminished magnetic properties compared to the stoichiometric SFMO. We also show that these samples exhibit superior MR values under low magnetic field and persisting up to temperatures as high as 400 K. - Graphical abstract: Evolution of the magnetization versus temperature under an applied magnetic field of 1000 Oe (left panel) and magnetoresistance versus applied magnetic field at 300 K (right panel) for strontium off-stoichiometric Sr{sub 2}FeMoO{sub 6} samples. - Highlights: • Strontium nonstoichiometric samples of Sr{sub 2}FeMoO{sub 6} are prepared by a citrate route. • The nonstoichiometric samples exhibit an increased Fe/Mo disorder in the structure. • We observed important changes in their magnetic and magnetoresistive properties. • Improved magnetoresistive properties for samples prepared with strontium excess.

  7. Characterization of feline serum-cobalt binding.

    PubMed

    Schnelle, Amy N; Barger, Anne M; MacNeill, Amy L; Mitchell, Mark M; Solter, Philip

    2015-06-01

    Oxidative stress inhibits albumin's ability to complex with cobalt. Feline serum-cobalt binding has not been described. The objective was to develop a cobalt binding test for use with feline serum, and correlate the results with other biochemical and cellular constituents in blood, and with clinical diseases of cats. A colorimetric test of cobalt binding, based on the oxidation-reduction reaction of Co(+2) and dithiothreitol, was developed using feline serum. The test was used to measure cobalt binding in stored serum from 176 cats presented to the University of Illinois Veterinary Teaching Hospital for a variety of disease conditions. Time-matched hematology and biochemical data, and clinical information, were obtained from the medical record of each cat and correlated with the serum-cobalt binding results. Serial dilution of feline serum with phosphate-buffered saline resulted in a highly linear decrease in serum-cobalt binding (r(2)  = .9984). Serum-cobalt binding of the clinical samples also correlated with albumin concentrations in a stepwise linear regression model (r(2)  = .425), and both cobalt binding and albumin were significantly decreased in cases of inflammation. Albumin and cobalt binding also shared significant correlations with several erythron variables, and serum concentration of total calcium and bilirubin. The correlation of cobalt binding measured by a colorimetric test with albumin concentration in the clinical samples and with serum dilution is consistent with feline albumin-cobalt complex formation. Hypoalbuminemia is the likely cause of reduced serum-cobalt binding in inflammation and the correlations observed between cobalt binding and other variables. © 2015 American Society for Veterinary Clinical Pathology.

  8. Potassium, rubidium, strontium, thorium, uranium, and the ratio of strontium-87 to strontium-86 in oceanic tholeiitic basalt

    USGS Publications Warehouse

    Tatsumoto, M.; Hedge, C.E.; Engel, A.E.J.

    1965-01-01

    The average concentrations of potassium, rubidium, strontium, thorium, and uranium in oceanic tholeiitic basalt are (in parts per million) K, 1400; Rb, 1.2; Sr, 120; Th, 0.2; and U, 0.1. The ratio Sr87 to Sr86 is about 0.702, that of K to U is 1.4 ?? 104, and of Th to U is 1.8. These amounts of K, Th, U, and radiogenic Sr87 are less than in other common igneous rocks. The ratios of Th to U and Sr87 to Sr 86 suggest that the source region of the oceanic tholeiites was differentiated from the original mantle material some time in the geologic past.

  9. COBALT Flight Demonstrations Fuse Technologies

    NASA Image and Video Library

    2017-06-07

    This 5-minute, 50-second video shows how the CoOperative Blending of Autonomous Landing Technologies (COBALT) system pairs new landing sensor technologies that promise to yield the highest precision navigation solution ever tested for NASA space landing applications. The technologies included a navigation doppler lidar (NDL), which provides ultra-precise velocity and line-of-sight range measurements, and the Lander Vision System (LVS), which provides terrain-relative navigation. Through flight campaigns conducted in March and April 2017 aboard Masten Space Systems' Xodiac, a rocket-powered vertical takeoff, vertical landing (VTVL) platform, the COBALT system was flight tested to collect sensor performance data for NDL and LVS and to check the integration and communication between COBALT and the rocket. The flight tests provided excellent performance data for both sensors, as well as valuable information on the integrated performance with the rocket that will be used for subsequent COBALT modifications prior to follow-on flight tests. Based at NASA’s Armstrong Flight Research Center in Edwards, CA, the Flight Opportunities program funds technology development flight tests on commercial suborbital space providers of which Masten is a vendor. The program has previously tested the LVS on the Masten rocket and validated the technology for the Mars 2020 rover.

  10. Macro- and microscopic properties of strontium doped indium oxide

    SciTech Connect

    Nikolaenko, Y. M.; Kuzovlev, Y. E.; Medvedev, Y. V.; Mezin, N. I.; Fasel, C.; Gurlo, A.; Schlicker, L.; Bayer, T. J. M.; Genenko, Y. A.

    2014-07-28

    Solid state synthesis and physical mechanisms of electrical conductivity variation in polycrystalline, strontium doped indium oxide In{sub 2}O{sub 3}:(SrO){sub x} were investigated for materials with different doping levels at different temperatures (T = 20–300 °C) and ambient atmosphere content including humidity and low pressure. Gas sensing ability of these compounds as well as the sample resistance appeared to increase by 4 and 8 orders of the magnitude, respectively, with the doping level increase from zero up to x = 10%. The conductance variation due to doping is explained by two mechanisms: acceptor-like electrical activity of Sr as a point defect and appearance of an additional phase of SrIn{sub 2}O{sub 4}. An unusual property of high level (x = 10%) doped samples is a possibility of extraordinarily large and fast oxygen exchange with ambient atmosphere at not very high temperatures (100–200 °C). This peculiarity is explained by friable structure of crystallite surface. Friable structure provides relatively fast transition of samples from high to low resistive state at the expense of high conductance of the near surface layer of the grains. Microscopic study of the electro-diffusion process at the surface of oxygen deficient samples allowed estimation of the diffusion coefficient of oxygen vacancies in the friable surface layer at room temperature as 3 × 10{sup −13} cm{sup 2}/s, which is by one order of the magnitude smaller than that known for amorphous indium oxide films.

  11. Disaccharidase deficiency.

    PubMed

    Bayless, T M; Christopher, N L

    1969-02-01

    This review of the literature and current knowledge concerning a nutritional disorder of disaccharidase deficiency discusses the following topics: 1) a description of disorders of disaccharide digestion; 2) some historical perspective on the laboratory and bedside advances in the past 10 years that have helped define a group of these digestive disorders; 3) a classification of conditions causing disaccharide intolerance; and 4) a discussion of some of the specific clinical syndromes emphasizing nutritional consequences of these syndromes. The syndromes described include congenital lactase deficiency, acquired lactase deficiency in teenagers and adults, acquired generalized disaccharidase deficiency secondary to diffuse mucosal damage, acquired lactose intolerance secondary to alterations in the intestinal transit, sucrase-isomaltase deficiencies, and other disease associations connected with lactase deficiency such as colitis.

  12. DRESS syndrome with autoimmune hepatitis from strontium ranelate.

    PubMed

    di Meo, Nicola; Gubertini, Nicoletta; Crocè, Lory; Tiribelli, Claudio; Trevisan, Giusto

    2016-05-01

    Strontium ranelate, which is used for postmenopausal osteoporosis, has been associated with drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, a severe, acute, potentially fatal, multisystem adverse drug reaction characterized by skin rash, fever, hematological abnormalities, and lymphadenopathy with involvement of several internal organs. We report the case of a woman who developed DRESS syndrome with a generalized maculopapular rash, eosinophilia, dyspnea, bilateral cervical lymphadenopathy, and reactivation of Epstein-Barr virus (EBV) with liver damage 3 weeks after administration of strontium ranelate for postmenopausal osteoporosis. Approximately 6 months after total remission of cutaneous symptoms, the patient developed autoimmune hepatitis. This case confirms that strontium ranelate should be considered as a possible factor in the etiopathology of DRESS syndrome as well as in the subsequent development of autoimmune hepatitis. The possibility of developing autoimmune hepatitis as a part of DRESS syndrome related to strontium ranelate use can occur months after the acute episode.

  13. Strontium-90 Error Discovered in Subcontract Laboratory Spreadsheet

    SciTech Connect

    D. D. Brown A. S. Nagel

    1999-07-31

    West Valley Demonstration Project health physicists and environment scientists discovered a series of errors in a subcontractor's spreadsheet being used to reduce data as part of their strontium-90 analytical process.

  14. A combined cesium-strontium extraction/recovery process

    SciTech Connect

    Horwitz, E.P.; Dietz, M.L.; Jensen, M.P.

    1996-03-01

    A new solvent extraction process for the simultaneous extraction of cesium and strontium from acidic nitrate media is described. This process uses a solvent formulation comprised of 0.05 M di-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 0.1 M Crown 100{prime} (a proprietary, cesium-selective derivative of dibenzo-18-crown-6), 1.2 M tributyl phosphate (TBP), and 5% (v/v) lauryl nitrile in an isoparaffinic hydrocarbon diluent. Distribution ratios for cesium and strontium from 4 M nitric acid are 4.13 and 3.46, respectively. A benchtop batch countercurrent extraction experiment indicates that >98% of the cesium and strontium initially present in the feed solution can be removed in only four extraction stages. Through proper choice of extraction and strip conditions, extracted cesium and strontium can be recovered either together or individually.

  15. Production of high-n strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Ye, S.; Zhang, X.; Killian, T. C.; Dunning, F. B.; Hiller, M.; Yoshida, S.; Burgdörfer, J.

    2014-04-01

    The photoexcitation of strontium Rydberg atoms with n ~ 300 is being examined using a crossed laser-atom beam approach to enable study of quasi-stable two-electron excited states and of strongly-coupled Rydberg systems.

  16. Biofortification of soy (Glycine max (L.) Merr.) with strontium ions.

    PubMed

    Sowa, Ireneusz; Wójciak-Kosior, Magdalena; Strzemski, Maciej; Dresler, Sławomir; Szwerc, Wojciech; Blicharski, Tomasz; Szymczak, Grażyna; Kocjan, Ryszard

    2014-06-11

    Soy (Glycine max (L.) Merr.) is an annual plant cultivated worldwide mostly for food. Moreover, due to its pharmacological properties it is widely used in pharmacy for alleviating the symptoms of osteoporosis. The aim of the present study was to investigate the biofortification of soy treated with various concentrations of strontium. Soy was found to have a strong capacity to absorb Sr(2+) (bioconcentration factor higher than 1). A positive linear correlation (R(2) > 0.98) between the amount of strontium in the growth medium and its content in the plant was also observed. Moreover, at a concentration of 1.5 mM, strontium appeared to be nontoxic and even stimulated plant growth by approximately 19.4% and 22.6% of fresh weight for shoots and roots, respectively. Our research may be useful to obtain vegetable products or herbal preparations containing both phytoestrogens and strontium to prevent postmenopausal osteoporosis.

  17. Cobalt release from inexpensive jewellery: has the use of cobalt replaced nickel following regulatory intervention?

    PubMed

    Thyssen, Jacob Pontoppidan; Jellesen, Morten S; Menné, Torkil; Lidén, Carola; Julander, Anneli; Møller, Per; Johansen, Jeanne Duus

    2010-08-01

    Before the introduction of the EU Nickel Directive, concern was raised that manufacturers of jewellery might turn from the use of nickel to cobalt following the regulatory intervention on nickel exposure. The aim was to study 354 consumer items using the cobalt spot test. Cobalt release was assessed to obtain a risk estimate of cobalt allergy and dermatitis in consumers who would wear the jewellery. The cobalt spot test was used to assess cobalt release from all items. Microstructural characterization was made using scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). Cobalt release was found in 4 (1.1%) of 354 items. All these had a dark appearance. SEM/EDS was performed on the four dark appearing items which showed tin-cobalt plating on these. This study showed that only a minority of inexpensive jewellery purchased in Denmark released cobalt when analysed with the cobalt spot test. As fashion trends fluctuate and we found cobalt release from dark appearing jewellery, cobalt release from consumer items should be monitored in the future. Industries may not be fully aware of the potential cobalt allergy problem.

  18. Polar state in freestanding strontium titanate nanoparticles

    SciTech Connect

    Tyson, Trevor A. E-mail: sswong@bnl.gov Yu, Tian; Croft, Mark; Scofield, Megan E.; Bobb-Semple, Dara; Tao, Jing; Jaye, Cherno; Fischer, Daniel; Wong, Stanislaus S. E-mail: sswong@bnl.gov

    2014-09-01

    Monodispersed strontium titanate nanoparticles were prepared and studied in detail. It is found that ∼10 nm as-prepared stoichiometric nanoparticles are in a polar structural state (possibly with ferroelectric properties) over a broad temperature range. A tetragonal structure, with possible reduction of the electronic hybridization, is found as the particle size is reduced. In the 10 nm particles, no change in the local Ti-off centering is seen between 20 and 300 K. The results indicate that nanoscale motifs of SrTiO{sub 3} may be utilized in data storage as assembled nano-particle arrays in applications where chemical stability, temperature stability, and low toxicity are critical issues.

  19. Secondary laser cooling of strontium-88 atoms

    SciTech Connect

    Strelkin, S. A.; Khabarova, K. Yu. Galyshev, A. A.; Berdasov, O. I.; Gribov, A. Yu.; Kolachevsky, N. N.; Slyusarev, S. N.

    2015-07-15

    The secondary laser cooling of a cloud of strontium-88 atoms on the {sup 1}S{sub 0}–{sup 3}P{sub 1} (689 nm) intercombination transition captured into a magneto-optical trap has been demonstrated. We describe in detail the recapture of atoms from the primary trap operating on the strong {sup 1}S{sub 0}–{sup 1}P{sub 1} (461 nm) transition and determine the recapture coefficient κ, the number of atoms, and their temperature in the secondary trap as a function of experimental parameters. A temperature of 2 µK has been reached in the secondary trap at the recapture coefficient κ = 6%, which confirms the secondary cooling efficiency and is sufficient to perform metrological measurements of the {sup 1}S{sub 0}–{sup 3}P{sub 1} (698 nm) clock transition in an optical lattice.

  20. Cosine (Cobalt Silicide Growth Through Nitrogen-Induced Epitaxy) Process For Epitaxial Cobalt Silicide Formation For High Performance Sha

    DOEpatents

    Lim, Chong Wee; Shin, Chan Soo; Gall, Daniel; Petrov, Ivan Georgiev; Greene, Joseph E.

    2004-09-28

    A method for forming an epitaxial cobalt silicide layer on a MOS device includes sputter depositing cobalt in an ambient to form a first layer of cobalt suicide on a gate and source/drain regions of the MOS device. Subsequently, cobalt is sputter deposited again in an ambient of argon to increase the thickness of the cobalt silicide layer to a second thickness.

  1. Survey of strontium in mineral waters sold in Japan: relations of strontium to other minerals and evaluation of mineral water as a possible dietary source of strontium.

    PubMed

    Usuda, Kan; Kono, Koichi; Dote, Tomotaro; Watanabe, Misuzu; Shimizu, Hiroyasu; Kawasaki, Takashi; Hayashi, Satsuki; Nakasuji, Kazuo; Fujimoto, Keiichi; Lu, Bo

    2006-07-01

    The concentrations of strontium, calcium, and magnesium in 33 brands of natural mineral waters commercially available in Japan were determined by inductively coupled plasma-atomic emission spectrometry. The geometric mean values were 94.4 microg/L for strontium, 19.1 mg/L for calcium, and 2.82 mg/L for magnesium. Wide confidence intervals of 1.96-4539 microg/L for strontium, 0.865-421 mg/L for calcium, and 0.064-123 mg/L for magnesium were observed. The significant linear relationships among the three elements over a wide distribution range suggest that the synchronized variations of these elements are regulated by the natural ecosystem and not from accidental contamination from human activities or exceptionally high natural sources. Using the results of multiple linear regression analysis, the strontium concentration can be predicted by that of calcium with the appropriate power function. The results of this study suggest that mineral water can be an important nutritional source of strontium. As trace elements imbalance is often found in older patients with chronic renal failure, we propose that close attention of trace elements intake from trendy foods or beverages is necessary to prevent this hidden problem of a rapidly aging society.

  2. Pituitary deficiencies.

    PubMed

    Greco, Deborah S

    2012-02-01

    Diabetes insipidus, arising from damage to or congenital abnormalities of the neurohypophysis, is the most common pituitary deficiency in animals. Hypopituitarism and isolated growth hormone or thyrotropin deficiency may result in growth abnormalities in puppies and kittens. In addition, treatment of associated hormone deficiencies, such as hypothyroidism and hypoadrenocorticism, in patients with panhypopituitarism is vital to restore adequate growth in dwarfed animals. Secondary hypoadrenocorticism is an uncommon clinical entity; however differentiation of primary versus secondary adrenal insufficiency is of utmost importance in determining optimal therapy. This article will focus on the pathogenesis, diagnosis and treatment of hormone deficiencies of the pituitary gland and neurohypophysis. Copyright © 2012. Published by Elsevier Inc.

  3. Process for the recovery of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid.

  4. Process for the recovery of strontium from acid solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1992-03-31

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid. 5 figs.

  5. Method for liquid chromatographic extraction of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  6. Degenerate gases of strontium for studies of quantum magnetism

    NASA Astrophysics Data System (ADS)

    Barker, Daniel Schaeder

    We describe the construction and characterization of a new apparatus that can produce degenerate quantum gases of strontium. The realization of degenerate gases is an important first step toward future studies of quantum magnetism. Three of the four stable isotopes of strontium have been cooled into the degenerate regime. The experiment can make nearly pure Bose-Einstein condensates containing approximately 1x104 atoms, for strontium-86, and approximately 4x105 atoms, for strontium-84. We have also created degenerate Fermi gases of strontium-87 with a reduced temperature, T/TF of approximately 0.2. The apparatus will be able to produce Bose-Einstein condensates of strontium-88 with straightforward modifications. We also report the first experimental and theoretical results from the strontium project. We have developed a technique to accelerate the continuous loading of strontium atoms into a magnetic trap. By applying a laser addressing the 3P1 to 3 S1 transition in our magneto-optical trap, the rate at which atoms populate the magnetically-trapped 3P 2 state can be increased by up to 65%. Quantum degenerate gases of atoms in the metastable 3P0 and 3P2 states are a promising platform for quantum simulation of systems with long-range interactions. We have performed an initial numerical study of a method to transfer the ground state degenerate gases that we can currently produce into one of the metastable states via a three-photon transition. Numerical simulations of the Optical Bloch equations governing the three-photon transition indicate that >90% of a ground state degenerate gas can be transferred into a metastable state.

  7. Strontium isotopic stratigraphy utilizing authigenic dolomites in hemipelagic sediments

    SciTech Connect

    Baker, P.A. ); Kastner, M. ); Elderfield, H. )

    1990-05-01

    Authigenic dolomites commonly occur in organic-rich, continental margin marine sediments. These dolomites play a key role in the age dating of stratigraphic sections. The dolomites often are the only lithology amenable to paleomagnetic stratigraphy; they preserve siliceous microfossils against diagenetic; recrystallization, and provide useful strontium isotopic stratigraphic ages. Several potential sources of error frequently are unique to the use of authigenic dolomites in the strontium isotope methods. (1) The dolomites occur as cements of the host lithology, hence, they are not a pure phase. Potentially important contaminants during analysis include gypsum clay minerals, feldspars, and iron and manganese oxides. Strontium may occur as a structural substituent ion in these minerals or as a surface-adsorbed ion. Various leaching techniques have been tested to isolate dolomitic strontium. Purer dolomites and strontium-enriched dolomites often can be selected to ease these problems. (2) The dolomites form after the deposition of the host sediment, therefore, they record the diagenetic age not the depositional age. The stable isotopic composition of the dolomites can aid in selection of early formed samples. (3) The dolomites record pore-water strontium isotope compositions, not seawater isotopic compositions. This problem is also minimized by choosing dolomites formed near the sediment-water interface. (4) The dolomites formed near the sediment-water interface originated as rotodolomites and undergo subsequent burial diagenesis, creating a potential for later strontium isotope exchange. This problem is minimized by selecting fresh samples from the interior of nearly impermeable beds and nodules. Results from the Miocene Monterey Formation of California and from the Eocene through Pliocene Pisco basin of Peru show that authigenic dolomites can provide useful strontium isotopic age estimates.

  8. Porous allograft bone scaffolds: doping with strontium.

    PubMed

    Zhao, Yantao; Guo, Dagang; Hou, Shuxun; Zhong, Hongbin; Yan, Jun; Zhang, Chunli; Zhou, Ying

    2013-01-01

    Strontium (Sr) can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS) were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF) assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca)] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28 ± 0.23 µm/day vs. 2.60 ± 0.20 µm/day; p<0.05). Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes.

  9. Porous Allograft Bone Scaffolds: Doping with Strontium

    PubMed Central

    Zhao, Yantao; Guo, Dagang; Hou, Shuxun; Zhong, Hongbin; Yan, Jun; Zhang, Chunli; Zhou, Ying

    2013-01-01

    Strontium (Sr) can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS) were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF) assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca)] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28±0.23 µm/day vs. 2.60±0.20 µm/day; p<0.05). Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes. PMID:23922703

  10. Strontium- and zinc-alginate hydrogels for bone tissue engineering.

    PubMed

    Place, Elsie S; Rojo, Luis; Gentleman, Eileen; Sardinha, José P; Stevens, Molly M

    2011-11-01

    The development of bone replacement materials is an important healthcare objective due to the drawbacks of treating defects with bone autografts. In this work we propose a bone tissue engineering approach in which arginine-glycine-aspartic acid (RGD)-modified alginate hydrogels are crosslinked with bioactive strontium and zinc ions as well as calcium. Strontium was chosen for its ability to stimulate bone formation, and zinc is essential for alkaline phosphatase (ALP) activity. Calcium and strontium gels had similar stiffnesses but different stabilities over time. Strontium gels made with alginate with a high percentage of guluronic acid residues (high G) were slow to degrade, whereas those made with alginate rich in mannuronic acid (high M) degraded more quickly, and supported proliferation of Saos-2 osteoblast-like cells. After an initial burst, strontium release from alginate gels was steady and sustained, and the magnitude of release from high M gels was biologically relevant. Saos-2 cultured within alginate gels upregulated the osteoblast phenotypic marker genes RUNX2, collagen I (COL1A1) and bone sialoprotein (BSP), and ALP protein activity was highest in alginate gels cast with strontium ions. This strategy has the potential to be combined with other alginate-based systems for bone tissue engineering, or adapted to other tissue engineering applications.

  11. Strontium ranelate: a new paradigm in the treatment of osteoporosis.

    PubMed

    Reginster, J-Y; Deroisy, R; Jupsin, I

    2003-02-01

    Not one of the currently available medications has, so far, unequivocally demonstrated its ability to fully prevent the occurrence of new vertebral or peripheral osteoporotic fractures once osteoporosis is established. Therefore, several new therapies are currently under development to optimize the risk/benefit ratio of osteoporosis treatment. Strontium ranelate is composed of an organic moiety (ranelic acid) and of two atoms of stable nonradioactive strontium. In vitro, strontium ranelate increases collagen and noncollagenic proteins synthesis by mature osteoblast enriched cells. The effects of strontium ranelate on bone formation were confirmed as strontium ranelate enhanced pre-osteoblastic cell replication. The stimulation by strontium ranelate of the replication of osteoprogenitor cell and collagen, as well as noncollagenic protein synthesis in osteoblasts, provides substantial evidence to categorize strontium ranelate as a bone-forming agent. In the isolated rat osteoclast assay, a pre-incubation of bone slices with strontium ranelate induced a dose- dependent inhibition of the bone resorbing activity of treated rat osteoclast. Strontium ranelate also dose-dependently inhibited, in a chicken bone marrow culture, the expression of both carbonic anhydrase II and the alpha-subunit of the vitronectin receptor. These effects showing that strontium ranelate significantly affects bone resorption due to a direct and/or matrix-mediated inhibition of osteoclast activity and also inhibits osteoclasts differentiation, are compatible with the profile of an anti-resorptive drug. In normal rats, administration of strontium ranelate induces an improvement in the mechanical properties of the humerus and/or the lumbar vertebra associated with a commensurate increase in bone dimension, shaft and volume. Strontium ranelate was administered in 160 early postmenopausal women, in a 24-month, double-blind, placebo-controlled, prospective randomized study. Daily oral dose of 125 mg

  12. Strontium ranelate normalizes bone mineral density in osteopenic patients.

    PubMed

    Malaise, Olivier; Bruyere, Olivier; Reginster, Jean-Yves

    2007-08-01

    To assess the capacity of strontium ranelate to restore normal bone mineral density (WHO definition: T-score >or=-1) in post-menopausal osteopenic women (T-score between -1 and -2.5) at baseline. Post-hoc analysis from SOTI and TROPOS studies of 1428 patients randomly assigned to receive either 2 g of strontium ranelate a day or placebo for three years. Bone mineral density was measured at baseline and each year for three years. Results were analyzed on an intention-to-treat basis. At lumbar spine, after one, two and three years of treatment with strontium ranelate, 26.4, 42.1 and 58.2% respectively of osteopenic patients normalized their bone mineral density, compared with 6.6, 8.9 and 11.9% in the placebo group (all p<0.001). At total hip, the percentage of patients normalizing their bone mineral density was 5.4, 10.0 and 19.6% in the strontium ranelate group and 1.8, 1.4 and 1.6% in the placebo one (all p<0.001). Strontium ranelate is able to normalize bone mineral density in a significant proportion of osteopenic patients after one, two and three years of treatment. The clinical relevance of these results should be confirmed by direct demonstration of the anti-fracture efficacy of strontium ranelate in osteopenic patients.

  13. Strontium signaling: molecular mechanisms and therapeutic implications in osteoporosis.

    PubMed

    Saidak, Zuzana; Marie, Pierre J

    2012-11-01

    Osteoporosis is an important age-related bone disease characterized by increased bone turnover with insufficient bone formation relative to bone resorption. According to the current understanding of this disorder, anti-resorptive and anabolic drugs have been developed for therapeutic intervention. Another therapeutic approach consists of dissociating bone resorption and formation. Preclinical and clinical studies provided evidence that strontium (in the form of ranelate) induces beneficial effects on bone mass and resistance in animal models of bone loss and in osteoporotic patients. These effects are mediated in part by the pharmacological actions of strontium on bone metabolism, by reducing bone resorption and maintaining or increasing bone formation. Current pharmacological studies showed that strontium activates multiple signaling pathways in bone cells to achieve its pharmacological actions. Notably, activation of the calcium-sensing receptor by strontium in osteoclasts or osteoblasts leads to activation of phospholipase Cβ, inositol 1,4,5-triphosphate, release of intracellular Ca²⁺, and activation of MAPK ERK1/2 and Wnt/NFATc signaling. Strontium-mediated activation of these pathways results in the modulation of key molecules such as RANKL and OPG that control bone resorption, and to the regulation of genes promoting osteoblastic cell replication, differentiation and survival. This review focuses on the more recent knowledge of strontium signaling in bone cells and describes how the resulting pharmacological actions on bone metabolism have important therapeutic implications in the treatment of age-related bone loss and possibly other disorders.

  14. Polytypic transformations during the thermal decomposition of cobalt hydroxide and cobalt hydroxynitrate

    SciTech Connect

    Ramesh, Thimmasandra Narayan

    2010-06-15

    The isothermal decomposition of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature leads to the formation of Co{sub 3}O{sub 4}. The phase evolution during the decomposition process was monitored using powder X-ray diffraction. The transformation of cobalt hydroxide to cobalt oxide occurs via three phase mixture while cobalt hydroxynitrate to cobalt oxide occurs through a two phase mixture. The nature of the sample and its preparation method controls the decomposition mechanism. The comparison of topotactical relationship between the precursors to the decomposed product has been reported in relation to polytypism. - Graphical abstract: Isothermal thermal decomposition studies of cobalt hydroxide and cobalt hydroxynitrate at different intervals of temperature show the metastable phase formed prior to Co{sub 3}O{sub 4} phase.

  15. On the cobalt and cobalt oxide electrodeposition from a glyceline deep eutectic solvent.

    PubMed

    Sakita, Alan M P; Della Noce, Rodrigo; Fugivara, Cecílio S; Benedetti, Assis V

    2016-09-14

    The electrodeposition of cobalt and cobalt oxides from a glyceline deep eutectic solvent is reported. Cyclic voltammetry, chronoamperometry, scanning electron microscopy, and Raman spectroscopy are employed to study the Co deposition processes. Surface analysis reveals that metallic cobalt is deposited at potentials less negative than the current peak potential whereas cobalt oxides are detected and electrochemically observed when the deposition is done at more negative potentials. i-t transients are analyzed by applying the Scharifker and Hills (SH) theoretical model. It is concluded that cobalt deposition occurs via a progressive nucleation and growth mechanism for concentrations higher than 0.05 mol L(-1) cobalt ions. For concentrations ≤0.025 mol L(-1) cobalt ions and low overpotentials, the mechanism changes to instantaneous nucleation. The im-tm relationships of the SH model are used to determine the values of the kinetic parameters and the cobalt ion diffusion coefficient.

  16. Selected aspects of the action of cobalt ions in the human body.

    PubMed

    Czarnek, Katarzyna; Terpiłowska, Sylwia; Siwicki, Andrzej K

    2015-01-01

    Cobalt is widespread in the natural environment and can be formed as an effect of anthropogenic activity. This element is used in numerous industrial applications and nuclear power plants. Cobalt is an essential trace element for the human body and can occur in organic and inorganic forms. The organic form is a necessary component of vitamin B12 and plays a very important role in forming amino acids and some proteins in nerve cells, and in creating neurotransmitters that are indispensable for correct functioning of the organism. Its excess or deficiency will influence it unfavourably. Salts of cobalt have been applied in medicine in the treatment of anaemia, as well as in sport as an attractive alternative to traditional blood doping. Inorganic forms of cobalt present in ion form, are toxic to the human body, and the longer they are stored in the body, the more changes they cause in cells. Cobalt gets into the body in several ways: firstly, with food; secondly by the respiratory system; thirdly, by the skin; and finally, as a component of biomaterials. Cobalt and its alloys are fundamental components in orthopaedic implants and have been used for about 40 years. The corrosion of metal is the main problem in the construction of implants. These released metal ions may cause type IV inflammatory and hypersensitivity reactions, and alternations in bone modelling that lead to aseptic loosening and implant failure. The ions of cobalt released from the surface of the implant are absorbed by present macrophages, which are involved in many of the processes associated with phagocytose orthopaedic biomaterials particles and release pro-inflammatory mediators such as interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor α (TNF-α), and prostaglandin.

  17. Selected aspects of the action of cobalt ions in the human body

    PubMed Central

    Terpiłowska, Sylwia; Siwicki, Andrzej K.

    2015-01-01

    Cobalt is widespread in the natural environment and can be formed as an effect of anthropogenic activity. This element is used in numerous industrial applications and nuclear power plants. Cobalt is an essential trace element for the human body and can occur in organic and inorganic forms. The organic form is a necessary component of vitamin B12 and plays a very important role in forming amino acids and some proteins in nerve cells, and in creating neurotransmitters that are indispensable for correct functioning of the organism. Its excess or deficiency will influence it unfavourably. Salts of cobalt have been applied in medicine in the treatment of anaemia, as well as in sport as an attractive alternative to traditional blood doping. Inorganic forms of cobalt present in ion form, are toxic to the human body, and the longer they are stored in the body, the more changes they cause in cells. Cobalt gets into the body in several ways: firstly, with food; secondly by the respiratory system; thirdly, by the skin; and finally, as a component of biomaterials. Cobalt and its alloys are fundamental components in orthopaedic implants and have been used for about 40 years. The corrosion of metal is the main problem in the construction of implants. These released metal ions may cause type IV inflammatory and hypersensitivity reactions, and alternations in bone modelling that lead to aseptic loosening and implant failure. The ions of cobalt released from the surface of the implant are absorbed by present macrophages, which are involved in many of the processes associated with phagocytose orthopaedic biomaterials particles and release pro-inflammatory mediators such as interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor α (TNF-α), and prostaglandin. PMID:26557039

  18. Technical and business considerations of cobalt hydrometallurgy

    NASA Astrophysics Data System (ADS)

    Peek, Edgar; Åkre, Torjus; Asselin, Edouard

    2009-10-01

    Approximately 55,000 tonnes of cobalt are produced annually worldwide, which represents an estimated 1-3 billion in annual sales depending on cobalt price changes. Cobalt is a common impurity in both non-ferrous mineral sulfide and oxide processing. In this paper some business and technical considerations are presented to facilitate the decision-making process required to produce either an intermediate or a finished cobalt product via a hydrometallurgical route. Methods currently available and practiced for the recovery of cobalt are considered, and process requirements up- and down-stream associated with each chosen method are discussed. In particular, some environmental, energy, or other sustainable development implications of each process are mentioned. An outlook on the future of the cobalt industry and anticipated future trends is included.

  19. Interaction of cobalt ions with carboxypeptidase A.

    PubMed

    Moratal, J M; Castells, J; Donaire, A; Salgado, J; Jiménez, H R; Domingo, R

    1994-01-01

    The interaction of cobalt(II) with native and cobalt(II)-substituted carboxypeptidase has been investigated, at pH 7.5, by electronic absorption and 1H NMR spectroscopies. The reaction of the cobalt(II) uptake by the metalloenzyme [MCPA] (M = Zn or Co) occurs very slowly and a bimetallic complex, [MCPA(Co)], is formed. On the basis of the 1H NOE experiments, the isotropically shifted proton resonances were assigned as belonging to a coordinated histidine residue. 1H NMR titrations of [ZnCPA(Co)] with zinc(II) show that the zinc ion does not compete with cobalt for binding to the noncatalytic site. The temperature dependence of the isotropic shifts, molar absorbance, and longitudinal relaxation time values are indicative of a five-coordinated geometry for the cobalt ion. The identification of the noncatalytic cobalt binding site is also discussed.

  20. Infiltrated lanthanum strontium chromite anodes for solid oxide fuel cells: Structural and catalytic aspects

    NASA Astrophysics Data System (ADS)

    Oh, Tae-Sik; Yu, Anthony S.; Adijanto, Lawrence; Gorte, Raymond J.; Vohs, John M.

    2014-09-01

    Infiltration is a widely used fabrication method for solid oxide fuel cell (SOFC) composite electrodes. Here we report a study of the structure and electrocatalytic properties of SOFC anodes composed of a layer of lanthanum, strontium chromite (La0.8Sr0.2CrO3, LSCr), both with and without added transition metal dopants, infiltrated into a porous yttria-stabilized zirconia (YSZ) matrix. The structural evolution of the electrode upon reduction and under typical SOFC operating conditions is compared to that reported previously for La0.8Sr0.2Cr0.5Mn0.5O3-YSZ composite anodes. For the transition metal doped materials, a portion of the metal dopants were found to be exsolved from the LSCr lattice upon reduction and to be effective in promoting electro-oxidation of hydrogen. Exsolved cobalt particles were also found to be relatively stable when exposed to hydrocarbon fuels with low activity for the formation of carbon deposits.

  1. Growth and micro structural studies on Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) buffer layers

    NASA Technical Reports Server (NTRS)

    Srinivas, S.; Pinto, R.; Pai, S. P.; Dsousa, D. P.; Apte, P. R.; Kumar, D.; Purandare, S. C.; Bhatnagar, A. K.

    1995-01-01

    Microstructure of Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) of radio frequency magnetron sputtered buffer layers was studied at various sputtering conditions on Si (100), Sapphire and LaAlO3 (100) substrates. The effect of substrate temperatures up to 800 C and sputtering gas pressures in the range of 50 mTorr. of growth conditions was studied. The buffer layers of YSZ and STO showed a strong tendency for columnar growth was observed above 15 mTorr sputtering gas pressure and at high substrate temperatures. Post annealing of these films in oxygen atmosphere reduced the oxygen deficiency and strain generated during growth of the films. Strong c-axis oriented superconducting YBa2Cu3O7-x (YBCO) thin films were obtained on these buffer layers using pulsed laser ablation technique. YBCO films deposited on multilayers of YSZ and STO were shown to have better superconducting properties.

  2. [Neurotoxic effects of cobalt: an open question].

    PubMed

    Catalani, S; Apostoli, P

    2011-01-01

    Increased cobalt levels have been associated with neurological diseases (hand tremor, incoordination, cognitive decline, depression, vertigo, hearing loss and visual changes) in addition to "classic" and known cardiac diseases (arrhythmias and cardiomyopathies) and allergic or endocrine symptoms. Cobalt neurotoxicity is reported in isolated cases: old occupational or iatrogenic exposures and more recent releases of metallic ions by prosthesis. The studies of these cases have revealed a typical symptomatology of cobalt probably due to its ability to induce oxidative stress and mitochondrial alterations.

  3. Cobalt-catalyzed C-H borylation.

    PubMed

    Obligacion, Jennifer V; Semproni, Scott P; Chirik, Paul J

    2014-03-19

    A family of pincer-ligated cobalt complexes has been synthesized and are active for the catalytic C-H borylation of heterocycles and arenes. The cobalt catalysts operate with high activity and under mild conditions and do not require excess borane reagents. Up to 5000 turnovers for methyl furan-2-carboxylate have been observed at ambient temperature with 0.02 mol % catalyst loadings. A catalytic cycle that relies on a cobalt(I)-(III) redox couple is proposed.

  4. Mineral resource of the month: cobalt

    USGS Publications Warehouse

    Shedd, Kim B.

    2009-01-01

    Cobalt is a metal used in numerous commercial, industrial and military applications. On a global basis, the leading use of cobalt is in rechargeable lithium-ion, nickel-cadmium and nickel-metal hydride battery electrodes. Cobalt use has grown rapidly since the early 1990s, with the development of new battery technologies and an increase in demand for portable electronics such as cell phones, laptop computers and cordless power tools.

  5. Strontium-90 at the Hanford Site and its ecological implications

    SciTech Connect

    RE Peterson; TM Poston

    2000-05-22

    Strontium-90, a radioactive contaminant from historical operations at the U.S. Department of Energy (DOE) Hanford Site, enters the Columbia River at several locations associated with former plutonium production reactors at the Site. Strontium-90 is of concern to humans and the environment because of its moderately long half-life (29.1 years), its potential for concentrating in bone tissue, and its relatively high energy of beta decay. Although strontium-90 in the environment is not a new issue for the Hanford Site, recent studies of near-river vegetation along the shoreline near the 100 Areas raised public concern about the possibility of strontium-90-contaminated groundwater reaching the riverbed and fall chinook salmon redds. To address these concerns, DOE asked Pacific Northwest National Laboratory (PNNL) to prepare this report on strontium-90, its distribution in groundwater, how and where it enters the river, and its potential ecological impacts, particularly with respect to fall chinook salmon. The purpose of the report is to characterize groundwater contaminants in the near-shore environment and to assess the potential for ecological impact using salmon embryos, one of the most sensitive ecological indicators for aquatic organisms. Section 2.0 of the report provides background information on strontium-90 at the Hanford Site related to historical operations. Public access to information on strontium-90 also is described. Section 3.0 focuses on key issues associated with strontium-90 contamination in groundwater that discharges in the Hanford Reach. The occurrence and distribution of fall chinook salmon redds in the Hanford Reach and characteristics of salmon spawning are described in Section 4.0. Section 5.0 describes the regulatory standards and criteria used to set action levels for strontium-90. Recommendations for initiating additional monitoring and remedial action associated with strontium-90 contamination at the Hanford Site are presented in Section 6

  6. The respiratory effects of cobalt

    SciTech Connect

    Cugell, D.W.; Morgan, W.K.; Perkins, D.G.; Rubin, A. )

    1990-01-01

    We studied seven subjects with certain manifestations of cobalt-induced lung disease. All worked with cobalt and were involved in either the production or use of hard metal. The mode of presentation varied from an acute hypersensitivity pneumonitis that cleared completely when exposure ceased to progressive severe interstitial fibrosis of the lungs. In one subject reexposure was followed by a recurrence of the symptoms. All subjects showed restrictive ventilatory impairment and a reduction of their diffusing capacity. The radiologic appearances varied greatly. While two subjects had clear roentgenograms with small lung volumes, others had a micronodular pattern or small blotchy nodular infiltrates, and one had diffuse reticulonodulation as is seen in cryptogenic fibrosing alveolitis. The pathologic appearances varied between desquamative interstitial pneumonia and overt mural fibrosis of the alveoli. Six of the seven patients had multinucleated giant cells in their biopsy specimens or bronchoalveolar lavage fluid.

  7. Solution for Depositing an Electroless Cobalt Alloy.

    DTIC Science & Technology

    SOLUTIONS(MIXTURES), *ELECTROLESS PLATING), (*PATENTS, ELECTROLESS PLATING), (*COBALT ALLOYS, ELECTROLESS PLATING), ADDITIVES, SODIUM COMPOUNDS... TUNGSTATES , POTASSIUM COMPOUNDS, NICKEL COMPOUNDS, SULFATES, THIOUREA, MAGNETIC PROPERTIES

  8. Strontium: new drug. Postmenopausal osteoporosis: too many unknowns.

    PubMed

    2005-12-01

    (1) Strontium ranelate is marketed in the European Union for the treatment of postmenopausal osteoporosis. Strontium, a cation closely related to calcium, was already used for this purpose in the 1950s but was abandoned because it caused bone mineralization disorders (mainly due to the high doses used at the time). (2) Strontium has only been compared with placebo: there are no clinical trials versus a diphosphonate. (3) On the basis of bone mineral density, two dose-finding studies suggested that, in women who are also taking calcium and vitamin D, the effective minimal dose of strontium is 1 g/day for primary prevention and 2 g/day for secondary prevention. (4) In secondary prevention, a randomised, double-blind trial (SOTI) involving 1649 postmenopausal women who had already had an osteoporotic fracture and were also taking calcium + vitamin D, showed that 2 g strontium daily reduced the risk of symptomatic vertebral fractures compared with placebo (11.3% versus 17.4%) after three years of treatment. (5) Another randomised, double-blind trial (TROPOS) involved 5091 women with osteoporosis of the femur. After three years of treatment with calcium, vitamin D, and either 2 g/day strontium or placebo, the risk of non vertebral osteoporotic fracture was lower in the strontium arm (10.9% versus 9.1%; relative risk 0.85, 95% confidence interval 0.71-1.01), although the difference was only just significant (p = 0.05). This trial failed to show that strontium reduced the risk of femoral fracture. A retrospective subgroup analysis raised the possibility of a preventive effect on hip fracture in patients aged over 74 years, but again the difference had only borderline significance (relative risk 0.64, confidence interval 0.412-0.997). (6) The SOTI and TROPOS studies were subsequently pooled for analysis. A retrospective subgroup analysis of women aged over 80 suggested some efficacy on non vertebral fractures, but this remains to be confirmed in a comparative trial with

  9. Oxidation of low cobalt alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  10. Zinc deficiency.

    PubMed

    Tuerk, Melanie J; Fazel, Nasim

    2009-03-01

    Zinc plays an essential role in numerous biochemical pathways. Zinc deficiency affects many organ systems, including the integumentary, gastrointestinal, central nervous system, immune, skeletal, and reproductive systems. This article aims to discuss zinc metabolism and highlights a few of the diseases associated with zinc deficiency. Zinc deficiency results in dysfunction of both humoral and cell-mediated immunity and increases the susceptibility to infection. Supplementation of zinc has been shown to reduce the incidence of infection as well as cellular damage from increased oxidative stress. Zinc deficiency is also associated with acute and chronic liver disease. Zinc supplementation protects against toxin-induced liver damage and is used as a therapy for hepatic encephalopathy in patients refractory to standard treatment. Zinc deficiency has also been implicated in diarrheal disease, and supplementation has been effective in both prophylaxis and treatment of acute diarrhea. This article is not meant to review all of the disease states associated with zinc deficiency. Rather, it is an introduction to the influence of the many roles of zinc in the body, with an extensive discussion of the influence of zinc deficiency in selected diseases. Zinc supplementation may be beneficial as an adjunct to treatment of many disease states.

  11. Eu(2+) luminescence in strontium aluminates.

    PubMed

    Dutczak, D; Jüstel, T; Ronda, C; Meijerink, A

    2015-06-21

    The luminescence properties of Eu(2+) doped strontium aluminates are reported and reviewed for a variety of aluminates, viz. SrAl12O19, SrAl4O7, Sr4Al14O25, SrAl2O4 and Sr3Al2O6. The aim of the research is to investigate the role of local coordination and covalency of the aluminate host lattice, related to the Sr/Al ratio, on the optical properties of the Eu(2+) ion. The UV and VUV excited luminescence spectra as well as luminescence decay curves were recorded to characterize the luminescence properties of the investigated aluminates. The emission of Eu(2+) ions varies over a wide spectral range, from ultraviolet (UV) to red, for the series of aluminates. The variation in emission color can be related to the crystal-field splitting of the 5d levels and the covalent interaction with the surrounding oxygen anions. In the least covalent material, viz. SrAl12O19:Eu(2+), narrow line emission due to the (6)P7/2-(8)S7/2 transition occurs at 4 K, indicating that the 4f(6)5d excited state is situated above the (6)P7/2(4f(7)) excited state around 360 nm. The most alkaline material, viz. Sr3Al2O6:Eu(2+) is the most covalent host and exhibits several d-f emission bands in the yellow to red spectral range due to the Eu(2+) ions located on different crystallographic Sr(2+) sites. The Eu(2+) emission spectra in the other aluminates confirm the trend that with increasing Sr/Al ratio the Eu(2+) emission shifts to longer wavelengths. Interesting differences are observed for the Eu(2+) from different crystallographic sites which cannot always be related with apparent differences in the first oxygen coordination sphere. The discussion gives insight into how in a similar class of materials, strontium aluminates, the emission color of Eu(2+) can be tuned over a wide spectral region.

  12. STRONTIUM-90 LIQUID CONCENTRATION SOLUBILITY CORRELATION IN THE HANFORD TANK WASTE OPERATIONS SIMULATOR

    SciTech Connect

    HOHL, T.; PLACE, D.; WITTMAN, R.

    2004-08-05

    A new correlation was developed to estimate the concentration of strontium-90 in a waste solution based on total organic carbon. This correlation replaces the strontium-90 wash factors, and when applied in the Hanford Tank Waste Operations Simulator, significantly reduced the estimated quantity of strontium-90 in the delivered low-activity waste feed. This is thought to be a more realistic estimate of strontium-90 than using the wash-factor method.

  13. The position of strontium ranelate in today's management of osteoporosis.

    PubMed

    Reginster, J-Y; Brandi, M-L; Cannata-Andía, J; Cooper, C; Cortet, B; Feron, J-M; Genant, H; Palacios, S; Ringe, J D; Rizzoli, R

    2015-06-01

    Osteoporosis accounts for about 3 % of total European health-care spending. The low proportion of costs for the pharmacological prevention of osteoporotic fracture means that it is highly cost saving, especially in patient with severe osteoporosis or patients who cannot take certain osteoporosis medications due to issues of contraindications or tolerability. Following recent regulatory changes, strontium ranelate is now indicated in patients with severe osteoporosis for whom treatment with other osteoporosis treatments is not possible, and without contraindications including uncontrolled hypertension, established, current or past history of ischaemic heart disease, peripheral arterial disease, and/or cerebrovascular disease. We review here today's evidence for the safety and efficacy of strontium ranelate. The efficacy of strontium ranelate in patients complying with the new prescribing information (i.e. severe osteoporosis without contraindications) has been explored in a multivariate analysis of clinical trial data, which concluded that the antifracture efficacy of strontium ranelate is maintained in patients with severe osteoporosis without contraindications and also demonstrated how the new target population mitigates risk. Strontium ranelate is therefore an important alternative in today's management of osteoporosis, with a positive benefit-risk balance, provided that the revised indication and contraindications are followed and cardiovascular risk is monitored. The bone community should be reassured that there remain viable alternatives in patients in whom treatment with other agents is not possible and protection against the debilitating effects of fracture is still feasible in patients with severe osteoporosis.

  14. Detecting infiltration and impacts of introduced water using strontium isotopes.

    PubMed

    Brinck, Elizabeth L; Frost, Carol D

    2007-01-01

    Water introduced to surface drainages, such as agricultural and roadway runoff, mine drainage, or coalbed natural gas (CBNG)-produced water, potentially can be of environmental concern. In order to mitigate potential environmental effects, it may be important to be able to trace water discharged to the surface as it infiltrates and interacts with near-surface aquifers. We have chosen to study water withdrawn during CBNG production for isotope tracing in the hyporheic zone because it poses a variety of economic, environmental, and policy issues in the Rocky Mountain states. Ground water quality must be protected as CBNG water is added to semiarid ecosystems. Strontium (Sr) isotopes are effective fingerprints of the aquifer from which water originates. In this study, CBNG water was found to have a higher (87)Sr/(86)Sr ratio than the local alluvial aquifer water. This measurable difference allows the strontium isotope ratio and concentration to be used as tracers of CBNG water following its discharge to the surface. The dissolution and mobilization of salts from soil are an important contributor to ground water quality degradation. In the Powder River basin of Wyoming, the soils are calcium carbonate-buffered systems. The chemical similarity of strontium to calcium allows it to substitute into calcium minerals and enabled us to use strontium isotopes to identify calcium salts mobilized from the soil. Strontium isotopes are an effective monitor of the source of ions and the volume and direction of introduced water flow in the hyporheic zone.

  15. Detecting infiltration and impacts of introduced water using strontium isotopes

    SciTech Connect

    Brinck, E.L.; Frost, C.D.

    2007-09-15

    Water introduced to surface drainages, such as agricultural and roadway runoff, mine drainage, or coalbed natural gas (CBNG)-produced water, potentially can be of environmental concern. In order to mitigate potential environmental effects, it may be important to be able to trace water discharged to the surface as it infiltrates and interacts with near-surface aquifers. We have chosen to study water withdrawn during CBNG production for isotope tracing in the hyporheic zone because it poses a variety of economic, environmental, and policy issues in the Rocky Mountain states. Ground water quality must be protected as CBNG water is added to semiarid ecosystems. Strontium (Sr) isotopes are effective fingerprints of the aquifer from which water originates. In this study, CBNG water was found to have a higher Sr-87/Sr-86 ratio than the local alluvial aquifer water. This measurable difference allows the strontium isotope ratio and concentration to be used as tracers of CBNG water following its discharge to the surface. The dissolution and mobilization of salts from soil are an important contributor to ground water quality degradation. In the Powder River basin of Wyoming, the soils are calcium carbonate-buffered systems. The chemical similarity of strontium to calcium allows it to substitute into calcium minerals and enabled us to use strontium isotopes to identify calcium salts mobilized from the soil. Strontium isotopes are an effective monitor of the source of ions and the volume and direction of introduced water flow in the hyporheic zone.

  16. Investigation of Varied Strontium-Transuranic Precipitation Chemistries for Crossflow

    SciTech Connect

    Nash, C.A.

    2000-07-27

    Precipitation chemistries for strontium and transuranic (TRU) removal have been tested for crossflow filterability and lanthanide removal with simulants of Hanford tank 241-AN-107 supernate. This is the initial work indicating the usefulness of a strontium and permanganate precipitation process as applied to the Hanford River Protection Project. Precipitations with both ferric and ferrous iron were shown to be at least two orders of magnitude less filterable than a 0.1 gpm/ft target average flux that was desired at the time. A precipitate from a strontium nitrate strike alone was found to filter easily and to make the desired average flux. Other chemistries tested included precipitant of lanthanum(III), nickel (II), calcium (II), and a redox chemistry using sodium permanganate. Of these chemistries a strontium and permanganate strike including calcium provided the highest filter flux compared to the other chemistries. It showed the most promise in lanthanide removal as well. This work provides a promising direction for further work to achieve both acceptable filterability and decontamination for Envelope C wastes to be treated by the Hanford River Protection Project. The work reported here was originally intended to satisfy needs for crossflow filter testing of a strontium and ferric precipitation method for treating Envelope C using a 241-AN-107 simulant.

  17. [Mechanisms of neurotransmitter release facilitation in strontium solutions].

    PubMed

    Mukhamed'iarov, M A; Kochunova, Iu O; Telina, E N; Zefirov, A L

    2008-02-01

    Mechanisms of neurotransmitter release facilitation were studied using electrophysiological recording of end-plate currents (EPC) and nerve ending (NE) responses after substitution of extracellular Ca ions with Sr ions at the frog neuromuscular junction. The solutions with 0.5 mM concentration of Ca ions (calcium solution) or 1 mM concentration of Sr ions (strontium solution) were used where baseline neurotransmitter release (at low-frequency stimulation) is equal. Decay of paired-pulse facilitation of EPC at calcium solutions with increase of interpulse interval from 5 to 500 ms was well described by three-exponential function consisting of early, first and second components. Facilitation at strontium solutions was significantly diminished due mainly to decrease of early and first components. At the same time, EPC facilitation with rhythmic stimulation (10 or 50 imp/s) at strontium solutions was significantly increased. Also more pronounced decrease of NE response 3rd phase, reflecting potassium currents was detected under rhythmic stimulation of 50 imp/s at strontium solutions comparing to calcium solutions. It was concluded that facilitation sites underlying first and early components had lower affinity to Sr ions than to Ca ions. The enhancement of frequency facilitation at strontium solutions is mediated by two mechanisms: more pronounced broadening of NE action potential and increase of bivalent cation influx due to feebly marked activation of Ca(2+)-dependent potassium current by Sr ions, and slower dynamics of Sr(2+) removal from NE axoplasm comparing to Ca(2+).

  18. Surface functionalization with strontium-containing nanocomposite coatings via EPD.

    PubMed

    Ma, Kena; Huang, Dan; Cai, Jing; Cai, Xinjie; Gong, Lingling; Huang, Pin; Wang, Yining; Jiang, Tao

    2016-10-01

    Metal orthopedic implants still face challenges in some compromised conditions, partly due to bio-inertness. The present study aimed to functionalize metallic implants with organic-inorganic nanocomposite (strontium-containing chitosan/gelatin) coatings through a simple single-step electrophoretic deposition under mild conditions. The surface characterization and in vitro cellular response were studied and compared with chitosan/gelatin (CS/G) coatings. SEM images suggested the inorganic nanoparticles may be encapsulated within or mixed with organic polymers. The XRD patterns showed that strontium carbonate was generated in the coatings. The TEM images revealed strontium-containing nanoparticles were released from the coatings in PBS. The continuous release after the initial burst release ensured the enduring effects of the functionalized surface. The tensile bond strength of the coatings to the substrates increased after the addition of strontium. In vitro cellular study confirmed that strontium-containing coatings supported the proliferation of MC3T3-E1 cells and exhibited excellent ability to enhance the differentiation of such pre-osteoblasts. Therefore, such organic-inorganic nanocomposite coatings are a promising candidate to functionalize orthopedic implant surfaces.

  19. Binding of dissolved strontium by Micrococcus luteus

    SciTech Connect

    Faison, B.D.; Cancel, C.A.; Lewis, S.N.; Adler, H.I. )

    1990-12-01

    Resting cells of Micrococcus luteus have been shown to remove strontium (Sr) from dilute aqueous solutions of SrCl{sub 2} at pH 7. Loadings of 25 mg of Sr per g of cell dry weight were achieved by cells exposed to a solution containing 50 ppm (mg/liter) of Sr. Sr binding occurred in the absence of nutrients and did not require metabolic activity. Initial binding was quite rapid (<0.5 h), although a slow, spontaneous release of Sr was observed over time. Sr binding was inhibited in the presence of polyvalent cations but not monovalent cations. Ca and Sr were bound preferentially over all other cations tested. Sr-binding activity was localized on the cell envelope and was sensitive to various chemical and physical pretreatments. Bound Sr was displaced by divalent ions or by H{sup +}. Other monovalent ions were less effective. Bound Sr was also removed by various chelating agents. It was concluded that Sr binding by M. luteus is a reversible equilibrium process. Both ion exchange mediated by acidic cell surface components and intracellular uptake may be involved in this activity.

  20. Binding of Dissolved Strontium by Micrococcus luteus

    PubMed Central

    Faison, Brendlyn D.; Cancel, Carmen A.; Lewis, Susan N.; Adler, Howard I.

    1990-01-01

    Resting cells of Micrococcus luteus have been shown to remove strontium (Sr) from dilute aqueous solutions of SrCl2 at pH 7. Loadings of 25 mg of Sr per g of cell dry weight were achieved by cells exposed to a solution containing 50 ppm (mg/liter) of Sr. Sr binding occurred in the absence of nutrients and did not require metabolic activity. Initial binding was quite rapid (<0.5 h), although a slow, spontaneous release of Sr was observed over time. Sr binding was inhibited in the presence of polyvalent cations but not monovalent cations. Ca and Sr were bound preferentially over all other cations tested. Sr-binding activity was localized on the cell envelope and was sensitive to various chemical and physical pretreatments. Bound Sr was displaced by divalent ions or by H+. Other monovalent ions were less effective. Bound Sr was also removed by various chelating agents. It was concluded that Sr binding by M. luteus is a reversible equilibrium process. Both ion exchange mediated by acidic cell surface components and intracellular uptake may be involved in this activity. PMID:16348370

  1. Producing Quantum Degenerate Gases of Strontium

    NASA Astrophysics Data System (ADS)

    Camargo, Francisco; Ding, Roger; Whalen, Joseph; Woehl, Germano; Dunning, Barry; Killian, Thomas

    2015-05-01

    We present our progress towards producing quantum degenerate gases of all four stable isotopes of strontium (84Sr, 86Sr, 87Sr, 88Sr) and isotopic mixtures. We characterize the performance of our broad-line (461 nm, 30.5 MHz), narrow-line (689 nm, 7.5 kHz) magneto-optical traps, and examine evaporative cooling for all four isotopes. The new apparatus will be used to create and study tunable long-range interactions by dressing with strongly-interacting Rydberg states. The ability to trap the four different isotopes allows a measure of control of these interactions through access to a range of attractive and repulsive interactions. Simultaneous trapping of different isotopes provides opportunities for novel laser cooling schemes for studying Bose-Bose and Bose-Fermi mixtures. Research supported by the AFOSR under grant no. FA9550-12-1-0267, the NSF under grants nos. 1301773 and 1205946, and the Robert A. Welch Foundation under grant no. C-0734.

  2. Coating of metal implant materials with strontium.

    PubMed

    Frank, Matthias J; Walter, Martin S; Tiainen, Hanna; Rubert, Marina; Monjo, Marta; Lyngstadaas, S Petter; Haugen, Håvard J

    2013-11-01

    The aim of this study was to show that cathodic polarization can be used for coating commercial implant surfaces with an immobilized but functional and bioavailable surface layer of strontium (Sr). Moreover, this study assessed the effect of fluorine on Sr-attachment. X-ray photoelectron spectroscopy revealed that addition of fluorine (F) to the buffer during coating increased surface Sr-amounts but also changed the chemical surface composition by adding SrF2 alongside of SrO whereas pre-treatment of the surface by pickling in hydrofluoric acid appeared to hinder Sr-attachment. Assessment of the bio-availability hinted at a positive effect of Sr on cell differentiation given that the surface reactivity of the original surface remained unchanged. Additional SrF2 on the surface appeared to reduce undesired surface contamination while maintaining the surface micro-topography and micro-morphology. Anyhow, this surface modification revealed to create nano-nodules on the surface.

  3. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  4. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  5. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium oxide...

  6. 10 CFR 31.10 - General license for strontium 90 in ice detection devices.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false General license for strontium 90 in ice detection devices... MATERIAL § 31.10 General license for strontium 90 in ice detection devices. (a) A general license is hereby issued to own, receive, acquire, possess, use, and transfer strontium 90 contained in ice detection...

  7. 10 CFR 31.10 - General license for strontium 90 in ice detection devices.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false General license for strontium 90 in ice detection devices... MATERIAL § 31.10 General license for strontium 90 in ice detection devices. (a) A general license is hereby issued to own, receive, acquire, possess, use, and transfer strontium 90 contained in ice detection...

  8. 10 CFR 31.10 - General license for strontium 90 in ice detection devices.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false General license for strontium 90 in ice detection devices... MATERIAL § 31.10 General license for strontium 90 in ice detection devices. (a) A general license is hereby issued to own, receive, acquire, possess, use, and transfer strontium 90 contained in ice detection...

  9. 10 CFR 31.10 - General license for strontium 90 in ice detection devices.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false General license for strontium 90 in ice detection devices... MATERIAL § 31.10 General license for strontium 90 in ice detection devices. (a) A general license is hereby issued to own, receive, acquire, possess, use, and transfer strontium 90 contained in ice detection...

  10. 10 CFR 31.10 - General license for strontium 90 in ice detection devices.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false General license for strontium 90 in ice detection devices... MATERIAL § 31.10 General license for strontium 90 in ice detection devices. (a) A general license is hereby issued to own, receive, acquire, possess, use, and transfer strontium 90 contained in ice detection...

  11. 10 CFR 35.433 - Decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Decay of strontium-90 sources for ophthalmic treatments... Brachytherapy § 35.433 Decay of strontium-90 sources for ophthalmic treatments. (a) Only an authorized medical physicist shall calculate the activity of each strontium-90 source that is used to determine the...

  12. 10 CFR 35.2433 - Records of decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Records of decay of strontium-90 sources for ophthalmic... Records § 35.2433 Records of decay of strontium-90 sources for ophthalmic treatments. (a) A licensee shall maintain a record of the activity of a strontium-90 source required by § 35.433 for the life of the...

  13. Strontium Adsorption and Desorption Reactions in Model Drinking Water Distribution Systems

    DTIC Science & Technology

    2014-02-04

    RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 11-04-2014 Journal Article Strontium adsorption and desorption reactions in model... strontium (Sr2+) adsorption to and desorption from iron corrosion products were examined in two model drinking water distribution systems (DWDS...used to control Sr2; desorption. calcium carbonate; drinking water distribution system; α-FeOOH; iron; strontium ; XANES Unclassified

  14. 40 CFR 721.10008 - Manganese strontium oxide (MnSrO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Manganese strontium oxide (MnSrO3... Specific Chemical Substances § 721.10008 Manganese strontium oxide (MnSrO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as manganese strontium...

  15. 10 CFR 35.2433 - Records of decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Records of decay of strontium-90 sources for ophthalmic... Records § 35.2433 Records of decay of strontium-90 sources for ophthalmic treatments. (a) A licensee shall maintain a record of the activity of a strontium-90 source required by § 35.433 for the life of the...

  16. 10 CFR 35.433 - Decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Decay of strontium-90 sources for ophthalmic treatments... Brachytherapy § 35.433 Decay of strontium-90 sources for ophthalmic treatments. (a) Only an authorized medical physicist shall calculate the activity of each strontium-90 source that is used to determine the...

  17. 40 CFR 721.10423 - Complex strontium aluminate, rare earth doped (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Complex strontium aluminate, rare... New Uses for Specific Chemical Substances § 721.10423 Complex strontium aluminate, rare earth doped... substances identified generically as complex strontium aluminate, rare earth doped (PMNs P-12-22, P-12-23,...

  18. 10 CFR 35.2433 - Records of decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Records of decay of strontium-90 sources for ophthalmic... Records § 35.2433 Records of decay of strontium-90 sources for ophthalmic treatments. (a) A licensee shall maintain a record of the activity of a strontium-90 source required by § 35.433 for the life of the...

  19. 10 CFR 35.433 - Decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Decay of strontium-90 sources for ophthalmic treatments... Brachytherapy § 35.433 Decay of strontium-90 sources for ophthalmic treatments. (a) Only an authorized medical physicist shall calculate the activity of each strontium-90 source that is used to determine the...

  20. Design and methodology of the phase 3 trials for the clinical development of strontium ranelate in the treatment of women with postmenopausal osteoporosis.

    PubMed

    Meunier, P J; Reginster, J Y

    2003-01-01

    The phase 3 program for strontium ranelate, a new oral agent in the treatment of women with postmenopausal osteoporosis, was aimed to assess the efficacy and safety of the daily oral dose of 2 g. This program was conducted in 12 countries, involved 75 centers, and was structured in 3 studies: FIRST (Fracture International Run-in for Strontium ranelate Trial), SOTI (Spinal Osteoporosis Therapeutic Intervention study) and TROPOS (TReatment Of Peripheral OSteoporosis). FIRST, a run-in open study, was designed to start the normalization of the calcium and vitamin D status of the patients, check all entry criteria, and ensure inclusion of a sufficient number of well-motivated patients in either one of the two therapeutic intervention protocols, SOTI or TROPOS: FIRST included 9,196 patients. SOTI and TROPOS were prospective, randomized, double-blind clinical trials comparing, in two parallel groups, the daily oral dose of 2 g of strontium ranelate with placebo, the patients of both groups receiving calcium and vitamin D according to their own deficiencies. The main objective of SOTI and TROPOS was to demonstrate a reduction in the incidence of postmenopausal women experiencing a new osteoporotic fracture (vertebral fracture in SOTI and nonvertebral fracture in TROPOS) over a 3-year treatment period, the total duration of the studies being 5 years. SOTI included 1,649 women with at least one osteoporotic vertebral fracture at inclusion and a lumbar BMD strontium ranelate in women with postmenopausal osteoporosis is a long-term program with the main statistical analysis after 3 years of treatment. Its aim is to demonstrate the effect of strontium ranelate on the axial and appendicular skeleton as well as its tolerability in osteoporotic patients with replete calcium and vitamin D stores.

  1. Cobalt Reduction Guidelines, Revision 1. Final report

    SciTech Connect

    Not Available

    1993-12-01

    This report, which updates and supersedes an earlier report (EPRI NP-6737) on the same subject, describes methods for establishing a program to identify nuclear power plant valves with high-cobalt hardfacing that are potential significant contributors to the cobalt inventory that is irradiated in the reactor core. The resulting radioactive cobalt isotope, cobalt-60, is a major contributor to plant radiation levels and therefore occupational doses received by plant operational and maintenance personnel. A methodology to determine whether hardfacing is actually required on specific valves is also described as is the physical, mechanical and wear properties of high-cobalt and potential replacement cobalt-free hardfacing and trim alloys. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. Current world-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The regulatory and industry code issues related to replacing and/or changing valve hardfacing materials are discussed. The actions and responsibilities of utility management in implementing an effective cobalt-reduction program are also delineated.

  2. Inhalation cancer risk assessment of cobalt metal.

    PubMed

    Suh, Mina; Thompson, Chad M; Brorby, Gregory P; Mittal, Liz; Proctor, Deborah M

    2016-08-01

    Cobalt compounds (metal, salts, hard metals, oxides, and alloys) are used widely in various industrial, medical and military applications. Chronic inhalation exposure to cobalt metal and cobalt sulfate has caused lung cancer in rats and mice, as well as systemic tumors in rats. Cobalt compounds are listed as probable or possible human carcinogens by some agencies, and there is a need for quantitative cancer toxicity criteria. The U.S. Environmental Protection Agency has derived a provisional inhalation unit risk (IUR) of 0.009 per μg/m(3) based on a chronic inhalation study of soluble cobalt sulfate heptahydrate; however, a recent 2-year cancer bioassay affords the opportunity to derive IURs specifically for cobalt metal. The mechanistic data support that the carcinogenic mode of action (MOA) is likely to involve oxidative stress, and thus, non-linear/threshold mechanisms. However, the lack of a detailed MOA and use of high, toxic exposure concentrations in the bioassay (≥1.25 mg/m(3)) preclude derivation of a reference concentration (RfC) protective of cancer. Several analyses resulted in an IUR of 0.003 per μg/m(3) for cobalt metal, which is ∼3-fold less potent than the provisional IUR. Future research should focus on establishing the exposure-response for key precursor events to improve cobalt metal risk assessment. Copyright © 2016. Published by Elsevier Inc.

  3. Cobalt improves nickel hydroxide electrodes for batteries

    NASA Technical Reports Server (NTRS)

    Lerner, S. R.; Seiger, H. N.

    1969-01-01

    Positive nickel hydroxide electrodes containing 20 mole percent of cobalt hydroxide are more efficient than when impregnated to the same degree by weight with nickel hydroxide alone. Charge-acceptance and oxygen-evolution tests indicate cobalt electrodes are more efficient than plain positive nickel hydroxide electrodes at all rates of charge.

  4. Serum cobalt in children with essential hypertension.

    PubMed

    Nicoloff, G; Angelova, M; Christova, I; Nikolov, A; Alexiev, A

    2006-01-01

    The effect of cobalt on the cardiovascular system is one of many aspects of cobalt metabolism in humans. Elastin and collagen are the main proteins of the vascular wall. The aims of this study were: 1) to determine serum cobalt concentrations in children with hypertension; and 2) to study the correlation between serum cobalt and some biological markers of the extracellular matrix of the vascular wall, i.e., anti-elastin and anti-collagen type IV antibodies. Patients showed statistically significant higher levels of systolic and diastolic blood pressure, and significantly lower serum cobalt concentrations, than controls. Children with hypertension showed significantly higher levels of total cholesterol (P = 0.0003) and collagen type IV IgM (P = 0.04). Collagen type IV IgG levels (P = 0.027) were lower than in controls. Serum cobalt in patients showed a correlation with systolic blood pressure (r = -0.44, P = 0.05), elastin IgM (r = 0.60, P = 0.007), and collagen type IV IgG (r = -0.46, P = 0.04). Our data suggest the existence of a correlation between changes in levels of serum cobalt, total cholesterol, anti-collagen type IV antibodies, and essential hypertension in children. This is the first study of serum cobalt in children with essential hypertension.

  5. Cobalt Derivatives as Promising Therapeutic Agents

    PubMed Central

    Heffern, Marie C.; Yamamoto, Natsuho; Holbrook, Robert J.; Eckermann, Amanda L.; Meade, Thomas J.

    2013-01-01

    Inorganic complexes are versatile platforms for the development of potent and selective pharmaceutical agents. Cobalt possesses a diverse array of properties that can be manipulated to yield promising drug candidates. Investigations into the mechanism of cobalt therapeutic agents can provide valuable insight into the physicochemical properties that can be harnessed for drug development. This review presents examples of bioactive cobalt complexes with special attention to their mechanisms of action. Specifically, cobalt complexes that elicit biological effects through protein inhibition, modification of drug activity, and bioreductive activation are discussed. Insights gained from these examples reveal features of cobalt that can be rationally tuned to produce therapeutics with high specificity and improved efficacy for the biomolecule or pathway of interest. PMID:23270779

  6. Healing of subtrochanteric atypical fractures after strontium ranelate treatment

    PubMed Central

    Negri, Armando Luis; Spivacow, Francisco Rodolfo

    2012-01-01

    Summary Oral bisphosphonates comprise the most widely prescribed class of antiosteoporotic drugs. Recent reports, however, suggest a link between prolonged bisphosphonate use and atypical low-energy, subtrochanteric fractures. We describe the clinical course of two patient treated for a long term with different bisphosphonates who developed subtrochanteric atypical fractures. They were treated initially with intramedullary rodding without pain disappearance or healing of the fracture. Strontium ranelate, a new orally administered agent for the treatment of osteoporosis, was given to these patients with complete closure of the fracture and pain disappearance after a few months. We conclude that based on the chronology of fracture healing and pain disappearance of our patients and published evidence that strontium ranelate can accelerate fracture healing in a rat model, that strontium ranelate had a positive anabolic effect that contributed to fracture healing that produced the secondary disappearance of pain. PMID:23289032

  7. Pulsed-periodic laser on RM helium and strontium transitions

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Yudin, N. A.; Polunin, Yu. P.; Reimer, I. V.; Khokhryakov, I. V.

    2008-01-01

    Conditions of generation of a running excitation wave in the active medium of gas lasers and efficiency of the running wave application for pumping of the active medium are considered by the example of a strontium vapor laser. It is demonstrated that the running excitation wave is generated directly in the active laser medium and is supported by the energy stored in the capacitive component of the impedance of a gas-discharge tube. Generation on the self-limited (21P1-21S0) transition of the helium atom at λ = 2058 nm and simultaneous generation on RM transitions of the strontium ion and strontium and helium atoms and on a number of neon atom transitions is first excited.

  8. Studies of Ultracold Strontium Atoms in an Optical Dipole Trap

    NASA Astrophysics Data System (ADS)

    Traverso, A. J.; Martinez de Escobar, Y. N.; Mickelson, P. G.; Killian, T. C.

    2008-05-01

    We survey recent experiments with ultracold strontium performed in our group. Trapping and cooling occurs in three stages: successive magneto-optical traps (MOTs) operating on 461 nm and 689 nm transitions of strontium, respectively, are loaded to cool atoms to a temperature of 1 μK. Finally, atoms are loaded into a far-off-resonance optical dipole trap (ODT). We examine the loading characteristics, thermalization, and lifetime of atoms held within the ODT. We also perform spectroscopy of atoms held within the ODT. During laser cooling, we are able to manipulate the energy levels of the atoms and shelve them into metastable states using 707 nm and 3 μm lasers. These experiments reveal interesting physics of ultracold strontium.

  9. Strontium ranelate in the prevention of osteoporotic fractures.

    PubMed

    Reginster, J-Y; Malaise, O; Neuprez, A; Bruyere, O

    2007-02-01

    Osteoporosis results from a decrease in bone strength yielding increased susceptibility to fractures. Hip and spine fractures are a major cause of morbidity and mortality in the elderly population. With an increasingly ageing world population, early prevention of bone loss is essential for adequate control of this condition. Strontium ranelate (PROTELOS((R))), an oral drug for postmenopausal osteoporosis, has been reported to decrease bone resorption and to stimulate bone formation. The efficacy in reducing vertebral fractures, non-vertebral including hip fractures, and the safety of strontium ranelate has been initially demonstrated over 3 years in the SOTI (Spinal Osteoporosis Therapeutic Intervention) and TROPOS (TReatment Of Peripheral OSteoporosis) studies and confirmed recently over up to 5 years. A preplanned analysis of a sub-group of patients aged 80 years and over showed that, currently, strontium ranelate is the only antiosteoporotic agent to reduce vertebral and non-vertebral fractures in this age group.

  10. 21 CFR 189.120 - Cobaltous salts and its derivatives.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Cobaltous salts and its derivatives. 189.120... or Use as Human Food § 189.120 Cobaltous salts and its derivatives. (a) Cobaltous salts are the... and to prevent “gushing.” (b) Food containing any added cobaltous salts is deemed to be adulterated...

  11. Loss of hypoxia-inducible factor 2 alpha in the lung alveolar epithelium of mice leads to enhanced eosinophilic inflammation in cobalt-induced lung injury.

    PubMed

    Proper, Steven P; Saini, Yogesh; Greenwood, Krista K; Bramble, Lori A; Downing, Nathaniel J; Harkema, Jack R; Lapres, John J

    2014-02-01

    Hard metal lung disease (HMLD) is an occupational lung disease specific to inhalation of cobalt-containing particles whose mechanism is largely unknown. Cobalt is a known hypoxia mimic and stabilizer of the alpha subunits of hypoxia-inducible factors (HIFs). Previous work revealed that though HIF1α contrib utes to cobalt toxicity in vitro, loss of HIF1α in the alveolar epithelial cells does not provide in vivo protection from cobalt-induced lung inflammation. HIF1α and HIF2α show unique tissue expression profiles, and HIF2α is known to be the predominant HIF mRNA isoform in the adult lung. Thus, if HIF2α activation by cobalt contributes to pathophysiology of HMLD, we hypothesized that loss of HIF2α in lung epithelium would provide protection from cobalt-induced inflammation. Mice with HIF2α-deficiency in Club and alveolar type II epithelial cells (ATIIs) (HIF2α(Δ/Δ)) were exposed to cobalt (60 µg/day) or saline using a subacute occupational exposure model. Bronchoalveolar lavage cellularity, cytokines, qRT-PCR, and histopathology were analyzed. Results show that loss of HIF2α leads to enhanced eosinophilic inflammation and increased goblet cell metaplasia. Additionally, control mice demonstrated a mild recovery from cobalt-induced lung injury compared with HIF2α(Δ/Δ) mice, suggesting a role for epithelial HIF2α in repair mechanisms. The expression of important cytokines, such as interleukin (IL)-5 and IL-10, displayed significant differences following cobalt exposure when HIF2α(Δ/Δ) and control mice were compared. In summary, our data suggest that although loss of HIF2α does not afford protection from cobalt-induced lung inflammation, epithelial HIF2α signaling does play an important role in modulating the inflammatory and repair response in the lung.

  12. Loss of Hypoxia-Inducible Factor 2 Alpha in the Lung Alveolar Epithelium of Mice Leads to Enhanced Eosinophilic Inflammation in Cobalt-Induced Lung Injury

    PubMed Central

    Proper, Steven P.; Saini, Yogesh; LaPres, John J.

    2014-01-01

    Hard metal lung disease (HMLD) is an occupational lung disease specific to inhalation of cobalt-containing particles whose mechanism is largely unknown. Cobalt is a known hypoxia mimic and stabilizer of the alpha subunits of hypoxia-inducible factors (HIFs). Previous work revealed that though HIF1α contrib utes to cobalt toxicity in vitro, loss of HIF1α in the alveolar epithelial cells does not provide in vivo protection from cobalt-induced lung inflammation. HIF1α and HIF2α show unique tissue expression profiles, and HIF2α is known to be the predominant HIF mRNA isoform in the adult lung. Thus, if HIF2α activation by cobalt contributes to pathophysiology of HMLD, we hypothesized that loss of HIF2α in lung epithelium would provide protection from cobalt-induced inflammation. Mice with HIF2α-deficiency in Club and alveolar type II epithelial cells (ATIIs) (HIF2αΔ/Δ) were exposed to cobalt (60 µg/day) or saline using a subacute occupational exposure model. Bronchoalveolar lavage cellularity, cytokines, qRT-PCR, and histopathology were analyzed. Results show that loss of HIF2α leads to enhanced eosinophilic inflammation and increased goblet cell metaplasia. Additionally, control mice demonstrated a mild recovery from cobalt-induced lung injury compared with HIF2αΔ/Δ mice, suggesting a role for epithelial HIF2α in repair mechanisms. The expression of important cytokines, such as interleukin (IL)-5 and IL-10, displayed significant differences following cobalt exposure when HIF2αΔ/Δ and control mice were compared. In summary, our data suggest that although loss of HIF2α does not afford protection from cobalt-induced lung inflammation, epithelial HIF2α signaling does play an important role in modulating the inflammatory and repair response in the lung. PMID:24218148

  13. Exposure to cobalt in the production of cobalt and cobalt compounds and its effect on the heart

    PubMed Central

    Linna, A; Oksa, P; Groundstroem, K; Halkosaari, M; Palmroos, P; Huikko, S; Uitti, J

    2004-01-01

    Aims: To investigate whether exposure to cobalt in cobalt plants has any measurable effect on the cardiovascular system. Methods: Occupational, cross sectional study, using a self administered questionnaire, blood pressure measurement, electrocardiography, and laboratory tests in which 203 male workers with at least one year of exposure to cobalt and 94 unexposed controls participated. Echocardiography was performed on a subset of 122 most highly exposed cobalt workers, of which 109 were analysed, and on 60 controls, of which 57 were analysed. Analysis of covariance and a multiple regression analysis were used to evaluate the data. Results: Two of the echocardiography parameters measured were associated with cobalt exposure. In the higher exposure group the left ventricular isovolumic relaxation time (mean 53.3, 49.1, and 49.7 ms in the high exposure, low exposure, and control groups respectively) and the deceleration time of the velocity of the early rapid filling wave (mean 194.3, 180.5, and 171.7 ms for those in the high exposure, low exposure, and control groups respectively) were prolonged, indicating altered left ventricular relaxation and early filling. Conclusion: Cumulative exposure to cobalt was found to be associated with the results of Doppler echocardiography measurements, indicating altered diastole. This finding supports the hypothesis that cobalt accumulation in the myocardium could affect myocardial function. Whether this finding has clinical implications remains to be evaluated. PMID:15477280

  14. Strontium and Magnesium in Water and in Crassostrea Calcite.

    PubMed

    Lerman, A

    1965-11-05

    Distribution of magnesium and strontium was determined between waters and calcites secreted by the oyster species Crassostrea virginica and C. rhizophorae in natural habitats at eight localities, from Maine to Puerto Rico. The concentration of strontium in the calcite shells increases with increasing temperature in the range 13 degrees to 25 degrees C, and also with increasing Sr(++)/Ca(++) molal ratio in the water. The concentration of magnesium in the shells increases irregularly with temperature, and it is apparently independent of the Mg(++)/Ca(++) ratio in the water. The greater variation with temperature in the distribution factor for magnesium may be related to genetic differences between semi-isolated populations.

  15. All-alkoxide synthesis of strontium-containing metal oxides

    DOEpatents

    Boyle, Timothy J.

    2001-01-01

    A method for making strontium-containing metal-oxide ceramic thin films from a precursor liquid by mixing a strontium neo-pentoxide dissolved in an amine solvent and at least one metal alkoxide dissolved in a solvent, said at least one metal alkoxide selected from the group consisting of alkoxides of calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, yttrium, lanthanum, antimony, chromium and thallium, depositing a thin film of the precursor liquid on a substrate, and heating the thin film in the presence of oxygen at between 550 and 700.degree. C.

  16. High Intensity 2-Photon Photoassociation Spectroscopy of Strontium

    NASA Astrophysics Data System (ADS)

    Nagel, S. B.; Martinez, Y. N.; Mickelson, P. G.; Killian, T. C.

    2007-06-01

    We perform high intensity, 2-photon photoassociation spectroscopy near the 461 nm ^1S0-^1P1 transition of strontium to determine the binding energy of the least bound level in the ground state atomic potential. Previous work by our group has constrained the value of the s-wave scattering length in both ^86Sr and ^88Sr. This work provides a more precise value of the s-wave scattering lengths using the newly-determined binding energy, thus informing efforts to attain quantum degeneracy in strontium.

  17. Control of magnetization reversal in oriented strontium ferrite thin films

    SciTech Connect

    Roy, Debangsu Anil Kumar, P. S.

    2014-02-21

    Oriented Strontium Ferrite films with the c axis orientation were deposited with varying oxygen partial pressure on Al{sub 2}O{sub 3}(0001) substrate using Pulsed Laser Deposition technique. The angle dependent magnetic hysteresis, remanent coercivity, and temperature dependent coercivity had been employed to understand the magnetization reversal of these films. It was found that the Strontium Ferrite thin film grown at lower (higher) oxygen partial pressure shows Stoner-Wohlfarth type (Kondorsky like) reversal. The relative importance of pinning and nucleation processes during magnetization reversal is used to explain the type of the magnetization reversal with different oxygen partial pressure during growth.

  18. First-principles calculations of strontium on Si(001)

    NASA Astrophysics Data System (ADS)

    Ashman, Christopher R.; Först, Clemens J.; Schwarz, Karlheinz; Blöchl, Peter E.

    2004-02-01

    This paper reports state-of-the-art electronic structure calculations on the deposition of strontium on the technologically relevant, (001) orientated silicon surface. We identified the surface reconstructions from 0 4/3 monolayers and relate them to experimentally reported data. A phase diagram is proposed. We predict phases at 1/6, 1/4, 1/2, 2/3, and 1 monolayers. Our results are expected to provide valuable information in order to understand heteroepitaxial growth of a prominent class of high-K oxides around SrTiO3. The insight obtained for strontium is expected to be transferable to other alkaline-earth metals.

  19. Strontium cobaltite oxygen sponge catalyst and methods of use

    DOEpatents

    Lee, Ho Nyung; Jeen, Hyoungjeen; Choi, Woo Seok; Biegalski, Michael; Folkman, Chad M.; Tung, I-Cheng; Fong, Dillon D.; Freeland, John W.; Shin, Dongwon; Ohta, Hiromichi; Chisholm, Matthew F.

    2017-01-24

    Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200.degree. C., from epitaxially stabilized, oxygen vacancy ordered SrCoO.sub.2.5 and thermodynamically unfavorable perovskite SrCoO.sub.3-.delta.. The fast, low temperature redox activity in SrCoO.sub.3-.delta. may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.

  20. Radiopaque Strontium Fluoroapatite Glass-Ceramics

    PubMed Central

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2–Al2O3–Y2O3–SrO–Na2O–K2O/Rb2O/Cs2O–P2O5–F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F – leucite, KAlSi2O6, (b) Sr5(PO4)3F – leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F – pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  1. Radiopaque Strontium Fluoroapatite Glass-Ceramics.

    PubMed

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2-Al2O3-Y2O3-SrO-Na2O-K2O/Rb2O/Cs2O-P2O5-F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F - leucite, KAlSi2O6, (b) Sr5(PO4)3F - leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F - pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F - Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite - pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal expansion (CTE). These

  2. Strontium stable isotope behaviour accompanying basalt weathering

    NASA Astrophysics Data System (ADS)

    Burton, K. W.; Parkinson, I. J.; Gíslason, S. G. R.

    2016-12-01

    The strontium (Sr) stable isotope composition of rivers is strongly controlled by the balance of carbonate to silicate weathering (Krabbenhöft et al. 2010; Pearce et al. 2015). However, rivers draining silicate catchments possess distinctly heavier Sr stable isotope values than their bedrock compositions, pointing to significant fractionation during weathering. Some have argued for preferential release of heavy Sr from primary phases during chemical weathering, others for the formation of secondary weathering minerals that incorporate light isotopes. This study presents high-precision double-spike Sr stable isotope data for soils, rivers, ground waters and estuarine waters from Iceland, reflecting both natural weathering and societal impacts on those environments. The bedrock in Iceland is dominantly basaltic, d88/86Sr ≈ +0.27, extending to lighter values for rhyolites. Geothermal waters range from basaltic Sr stable compositions to those akin to seawater. Soil pore waters reflect a balance of input from primary mineral weathering, precipitation and litter recycling and removal into secondary phases and vegetation. Rivers and ground waters possess a wide range of d88/86Sr compositions from +0.101 to +0.858. Elemental and isotope data indicate that this fractionation primarily results from the formation or dissolution of secondary zeolite (d88/86Sr ≈ +0.10), but also carbonate (d88/86Sr ≈ +0.22) and sometimes anhydrite (d88/86Sr ≈ -0.73), driving the residual waters to heavier or lighter values, respectively. Estuarine waters largely reflect mixing with seawater, but are also be affected by adsorption onto particulates, again driving water to heavy values. Overall, these data indicate that the stability and nature of secondary weathering phases, exerts a strong control on the Sr stable isotope composition of silicate rivers. [1] Krabbenhöft et al. (2010) Geochim. Cosmochim. Acta 74, 4097-4109. [2] Pearce et al. (2015) Geochim. Cosmochim. Acta 157, 125-146.

  3. Microwave-assisted fabrication of strontium doped apatite coating on Ti6Al4V.

    PubMed

    Zhou, Huan; Kong, Shiqin; Pan, Yan; Zhang, Zhiguo; Deng, Linhong

    2015-11-01

    Strontium has been shown to be a beneficial dopant to calcium phosphates when incorporated at nontoxic level. In the present work we studied the possibility of solution derived doping strontium into calcium phosphate coatings on titanium alloy Ti6Al4V based implants by a recently reported microwave-assisted method. By using this method strontium doped calcium phosphate nuclei were deposited to pretreated titanium alloy surface dot by dot to compose a crack-free coating layer. The presence of strontium in solution led to reduced roughness of the coating and finer nucleus size formed. In vitro study found that proliferation and differentiation of osteoblast cells seeded on the coating were influenced by strontium content in coatings, showing an increasing followed by a decreasing behavior with increasing substitution of calcium by strontium. It is suggested that this new microwave-assisted strontium doped calcium phosphate coatings may have great potential in implant modification.

  4. Variation in strontium isotope ratios of archaeological fauna in the Midwestern United States: a preliminary study

    USGS Publications Warehouse

    Hedman, Kristin M.; Curry, B. Brandon; Johnson, Thomas M.; Fullagar, Paul D.; Emerson, Thomas E.

    2009-01-01

    Strontium isotope values (87Sr/86Sr) in bone and tooth enamel have been used increasingly to identify non-local individuals within prehistoric human populations worldwide. Archaeological research in the Midwestern United States has increasingly highlighted the role of population movement in affecting interregional cultural change. However, the comparatively low level of geologic variation in the Midwestern United States might suggest a corresponding low level of strontium variation, and calls into question the sensitivity of strontium isotopes to identify non-local individuals in this region. Using strontium isotopes of archaeological fauna, we explore the degree of variability in strontium ratios across this region. Our results demonstrate measurable variation in strontium ratios and indicate the potential of strontium analysis for addressing questions of origin and population movement in the Midwestern United States.

  5. Advances in cobalt complexes as anticancer agents.

    PubMed

    Munteanu, Catherine R; Suntharalingam, Kogularamanan

    2015-08-21

    The evolution of resistance to traditional platinum-based anticancer drugs has compelled researchers to investigate the cytostatic properties of alternative transition metal-based compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. This perspective catalogues the development of antiproliferative cobalt complexes, and provides an in depth analysis of their mode of action. Early studies on simple cobalt coordination complexes, Schiff base complexes, and cobalt-carbonyl clusters will be documented. The physiologically relevant redox properties of cobalt will be highlighted and the role this plays in the preparation of hypoxia selective prodrugs and imaging agents will be discussed. The use of cobalt-containing cobalamin as a cancer specific delivery agent for cytotoxins will also be described. The work summarised in this perspective shows that the biochemical and biophysical properties of cobalt-containing compounds can be fine-tuned to produce new generations of anticancer agents with clinically relevant efficacies.

  6. Cobalt - poly(amido amine) superparamagnetic nanocomposites.

    PubMed

    Atwater, James E; Akse, James R; Holtsnider, John T

    2008-06-30

    Metallic cobalt-dendrimer nanocomposites were prepared using generation 5 Poly(amido amine) dendrimers with primary amino termini. Cobalt loading of ~38 atoms per dendrimer was determined by atomic absorption spectrophotometry. Magnetic properties of the cobalt-dendrimer nanocomposites were investigated across the temperature range from 2-300 K by SQUID magnetometry. Magnetization as a function of temperature and applied field strength was studied in zero field cooled samples. Magnetization-demagnetization curves (hysteresis loops) were also acquired at temperatures between 10 - 300 K. These results clearly indicate superparamagnetism for the nanocomposites with a characteristic blocking temperature of ~50 K.

  7. Cobalt - poly(amido amine) superparamagnetic nanocomposites

    PubMed Central

    Atwater, James E.; Akse, James R.; Holtsnider, John T.

    2010-01-01

    Metallic cobalt-dendrimer nanocomposites were prepared using generation 5 Poly(amido amine) dendrimers with primary amino termini. Cobalt loading of ~38 atoms per dendrimer was determined by atomic absorption spectrophotometry. Magnetic properties of the cobalt-dendrimer nanocomposites were investigated across the temperature range from 2–300 K by SQUID magnetometry. Magnetization as a function of temperature and applied field strength was studied in zero field cooled samples. Magnetization-demagnetization curves (hysteresis loops) were also acquired at temperatures between 10 – 300 K. These results clearly indicate superparamagnetism for the nanocomposites with a characteristic blocking temperature of ~50 K. PMID:20352068

  8. Growth of cobalt and cobalt disilicide on Si(100)

    NASA Astrophysics Data System (ADS)

    Gallego, J. M.; Miranda, R.; Molodtsov, S.; Laubschat, C.; Kaindl, G.

    1990-12-01

    The growth of Co on Si(100) and the initial stages of the formation of cobalt suicides have been studied by means of a multitechnique approach. Adsorption of Co on Si(100) at room temperature does not result in reaction and formation of a few ML-thick CoSi 2 overlayer, contrary to adsorption on (111) surfaces. Rather, a layer-by-layer growth of metallic Co with some Si interdiffused is observed. The formation of CoSi 2 requires annealing to 350°C, a temperature much lower than in the (111) surface. Annealing to 600° C results in additional Si-enrichment at the surface produced by disruption of the CoSi 2 overlayer. The thin CoSi 2 "template" layer, which is crucial to achieve epitaxial growth, contains Si at the outer surface, as demonstrated by chemical titration.

  9. Membrane-based separation technologies for cesium, strontium, and technetium

    SciTech Connect

    Kafka, T.

    1996-10-01

    This work is one of two parallel projects that are part of an ESP task to develop high-capacity, selective, solid extractants for cesium, strontium, and technetium from nuclear wastes. In this subtask, Pacific Northwest National Laboratory (PNNL) is collaborating with 3M, St. Paul, Minnesota, working in cooperation with IBC Advanced Technologies, American Fork, Utah.

  10. Discovery of rubidium, strontium, molybdenum, and rhodium isotopes

    SciTech Connect

    Parker, A.M.; Thoennessen, M.

    2012-07-15

    Currently, 31 rubidium, 35 strontium, 35 molybdenum, and 38 rhodium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  11. Active Calcium and Strontium Transport in Human Erythrocyte Ghosts

    PubMed Central

    Olson, Erik J.; Cazort, Ralph J.

    1969-01-01

    Both calcium and strontium could be transported actively from erythrocytes if adenosine triphosphate, guanosine triphosphate, or inosine triphosphate were included in the hypotonic medium used to infuse calcium or strontium into the cells. Acetyl phosphate and pyrophosphate were not energy sources for the transport of either ion. Neither calcium nor strontium transport was accompanied by magnesium exchange, and the addition of Mg++ to the reaction medium in a final concentration of 3.0 mmoles/liter did not promote the transport of either ion. In the absence of nucleotide triphosphates, the addition of 1.5 mmoles/liter of Sr++ to the reaction solution did not bring about active calcium transport and similarly 1.5 mmoles/liter of Ca++ did not bring about active strontium transport. The inclusion of 1.5 mmoles/liter of Ca++ or Sr++ in the reaction medium did not interfere with the transport of the other ion when the erythrocytes were infused with adenosine triphosphate. PMID:4304202

  12. Possible benefits of strontium ranelate in complicated long bone fractures.

    PubMed

    Alegre, Duarte Nuno; Ribeiro, Costa; Sousa, Carlos; Correia, João; Silva, Luís; de Almeida, Luís

    2012-02-01

    Osteoporosis drugs are prescribed to prevent fragility fractures, which is the principal aim of the management of osteoporosis. However, if fracture does occur, then it is also important to promote a fast and uneventful healing process. Despite this, little is known about the effect of osteoporosis drugs on bone healing in humans. Strontium ranelate is an osteoporosis agent that increases bone formation and reduces bone resorption and may therefore be beneficial in fracture healing. We report four cases of fracture non-union for up to 20 months. Treatment with strontium ranelate (2 g/day) for between 6 weeks and 6 months appeared to contribute to bone consolidation in the four cases. Animal studies support beneficial effects of strontium ranelate on bone healing via improvement of bone material properties and microarchitecture in the vicinity of the fracture. The clinical cases described herein provide new information on these effects, in the absence of randomized controlled studies on the clinical efficacy of pharmacological treatments in osteoporosis in fracture repair. Further studies are necessary. Fracture healing is an important topic in orthopedic research and is also a concern for patients with postmenopausal osteoporosis. Evidence from case reports and animal studies suggests that strontium ranelate improves bone microarchitecture and accelerates fracture healing. A positive effect of osteoporosis treatments on bone healing is an interesting possibility and merits further clinical research.

  13. Barium strontium titanate powder obtained by polymeric precursor method

    SciTech Connect

    Ries, A.; Simoes, A.Z.; Cilense, M.; Zaghete, M.A.; Varela, J.A

    2003-03-15

    Pure barium strontium titanate powder, with Ba/Sr ratio of 80/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 deg. C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.

  14. Laser-induced collisional autoionization in europium and strontium atoms.

    PubMed

    Buffa, R

    1995-01-15

    An experiment that involves laser-induced collisional autoionization in europium and strontium atoms is proposed and the spectral line shape of the cross section is calculated on the basis of data available in the literature. The feasibility of the experiment both in oven cells and in a crossed-atomic-beam geometry is discussed.

  15. Laser sources for precision spectroscopy on atomic strontium.

    PubMed

    Poli, N; Ferrari, G; Prevedelli, M; Sorrentino, F; Drullinger, R E; Tino, G M

    2006-04-01

    We present a new laser setup designed for high-precision spectroscopy on laser cooled atomic strontium. The system, which is entirely based on semiconductor laser sources, delivers 200 mW at 461 nm for cooling and trapping atomic strontium from a thermal source, 4 mW at 497 nm for optical pumping from the metastable P23 state, 12 mW at 689 nm on linewidth less than 1 kHz for second-stage cooling of the atomic sample down to the recoil limit, 1.2 W at 922 nm for optical trapping close to the "magic wavelength" for the 0-1 intercombination line at 689 nm. The 689 nm laser was already employed to perform a frequency measurement of the 0-1 intercombination line with a relative accuracy of 2.3 x 10(-11), and the ensemble of laser sources allowed the loading in a conservative dipole trap of multi-isotopes strontium mixtures. The simple and compact setup developed represents one of the first steps towards the realization of a transportable optical standards referenced to atomic strontium.

  16. Heavy ion recoil spectrometry of barium strontium titanate films

    NASA Astrophysics Data System (ADS)

    Stannard, W. B.; Johnston, P. N.; Walker, S. R.; Bubb, I. F.; Scott, J. F.; Cohen, D. D.; Dytlewski, N.; Martin, J. W.

    1995-05-01

    Thin films of barium strontium titanate have been analysed using heavy ion recoil spectrometry with 77 and 98 MeV 127I ions at the new heavy ion recoil facility at ANSTO, Lucas Heights. New calibration procedures have been developed for quantitative analysis. Energy spectra for each of the elements present reveal interdiffusion that was not previously known.

  17. Stable colloidal solutions of strontium hexaferrite hard magnetic nanoparticles.

    PubMed

    Trusov, Lev A; Vasiliev, Alexander V; Lukatskaya, Maria R; Zaytsev, Dmitry D; Jansen, Martin; Kazin, Pavel E

    2014-12-04

    Herein we demonstrate an approach to prepare a colloidal solution of strontium hexaferrite via a glass-ceramic route. The as obtained colloids are stable and resistive to aggregation or sedimentation. They reveal outstanding magnetic and magneto-optical properties because of their platelet-like anisotropic shape and high permanent magnetic moment.

  18. Strontium-90 and cesium-137 distribution in Baltic Sea waters

    SciTech Connect

    Lazarev, L.N.; Gedeonov, L.I.; Ivanova, L.M.; Stepanov, A.V.

    1988-09-01

    The strontium-90 and cesium-137 concentrations determined in 1983 in the Baltic Sea proper and the Gulf of Finland and in the Soviet Baltic rivers are furnished. The cesium-137 content has been found to be directly proportional to the salinity of the water. Significant influx of technogenic radioactive contaminants from the North to the Baltic Sea was noted in 1983.

  19. A new treatment for post-menopausal osteoporosis: strontium ranelate.

    PubMed

    Rizzoli, R

    2005-01-01

    Strontium ranelate is a new anti-osteoporotic agent which appears to reduce bone resorption by decreasing osteoclast differentiation and activity, and to stimulate bone formation by increasing replication of pre-osteoblast cells, leading to increased matrix synthesis. This review examines both the scientific rationale for its use in post-menopausal osteoporosis and the evidence of its antifracture efficacy. In the placebo-controlled, phase III trial Spinal Osteoporosis Therapeutic Intervention (SOTI) (no.=1442; mean age 69 yr), there was a 41% decrease over 3 yr in the number of patients with new vertebral fracture in the strontium ranelate (2 g/day) group vs placebo (p<0.001), and a 14.4% difference in lumbar bone mineral density (BMD) at 3 yr vs placebo. This reduction in vertebral fracture risk was already detected after 12 months (49% lower risk, p<0.001). The phase III TReatment Of Peripheral OSteoporosis (TROPOS) study assessed the efficacy of strontium ranelate (2 g/day) in preventing non-vertebral fracture in post-menopausal osteoporosis (no.=4932; mean age 77 yr). Strontium ranelate reduced non-vertebral fracture risk by 16% vs placebo (p=0.04) and hip fracture risk by 36% (p=0.031), in osteoporotic patients older than 74 yr. There was a concomitant increase in BMD throughout the study, reaching +8.2% (femoral neck) and +9.8% (total hip) at 3 yr. Strontium ranelate is thus a first-choice treatment of post-menopausal osteoporosis as it significantly reduces vertebral, non-vertebral and hip fracture risk in post-menopausal osteoporotic women, as well as having an excellent tolerability profile.

  20. Clinical effects of strontium ranelate in women with postmenopausal osteoporosis.

    PubMed

    Delmas, Pierre D

    2005-01-01

    Postmenopausal osteoporosis has long-term physical, psychological, and social consequences with a major impact on patients' daily life. Treatment for such a chronic disease needs to be clinically effective and well tolerated, and should ultimately result in a beneficial effect on quality of life. The antifracture efficacy of strontium ranelate, 2 g/day orally, an agent that appears to have dissociation effects on resorption and formation, has been assessed in two large, randomized, double-blind, placebo-controlled clinical studies: the Spinal Osteoporosis Therapeutic Intervention (SOTI) trial and the TReatment Of Peripheral Osteoporosis Study (TROPOS), including more than 6,700 postmenopausal women. Pending the results of TROPOS, a 3-year analysis of SOTI results shows that strontium ranelate significantly reduces new vertebral and clinical vertebral fracture incidence in postmenopausal osteoporotic women. This significant reduction in the risk of clinical and new vertebral fractures has been demonstrated as early as after 1 year of treatment (RR = 0.48, p = 0.003; and RR = 0.51, p < 0.001, respectively) and is maintained over 3 years (RR = 0.62, p < 0.001; and RR = 0.59, p < 0.001, respectively). This is accompanied by decreased back pain and body height loss in the strontium ranelate group compared with the placebo group. As strontium ranelate appears to improve clinical signs and is, furthermore, well tolerated especially in the upper gastrointestinal region, this treatment is expected to result in an improved health-related quality of life (HRQoL). Strontium ranelate thus offers significant clinical benefits in terms of efficacy, tolerability, and ease of administration in the treatment of postmenopausal women with vertebral osteoporotic fractures.

  1. Strontium Incorporation Into Calcite Generated by Bacterial Ureolysis

    NASA Astrophysics Data System (ADS)

    Fujita, Y.; Ingram, J. A.; Cortez, M. M.; Redden, G. D.; Smith, R. W.

    2002-12-01

    Strontium incorporation into calcite generated by bacterial ureolytic activity was investigated as part of a larger effort to evaluate the use of in situ urea hydrolysis for accelerating co-precipitation of trace metals and radionuclides in contaminated aquifers. 90Sr, a uranium fission product with a half-life of 29 years, is a significant subsurface contaminant at several Department of Energy facilities and could be immobilized using this remediation strategy. Experiments were conducted in a medium designed to simulate the groundwater of the Snake River Plain Aquifer in eastern Idaho, amended with strontium. Initially the solution was undersaturated with respect to calcite. As a model ureolytic organism, we used Bacillus pasteurii, a well-characterized bacterium known for high urease activity and previously shown to induce calcite precipitation in urea-amended medium. To gain information on the effect of the bacterial surfaces, we also looked at precipitation in the presence of a bacterial species that did not hydrolyze urea, as well as in the absence of bacteria. In the absence of bacterial ureolysis, carbonate precipitation was induced by addition of ammonium carbonate. All products were identified as calcite by X-ray diffraction. Strontium uptake was observed in all cases, but was greatest in the system including bacterial ureolysis. Sputter depth element profiling by time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed this finding, showing highest Sr:Ca ratios in the bacterially generated calcite throughout the depth (~350 nm) investigated. Environmental Scanning Electron Microscopy (ESEM) of the solids revealed regular crystals containing the outlines of embedded or entombed bacterial cells, suggesting that calcite precipitated directly on the cell surfaces when present. Analysis by X-ray Absorption Near Edge Spectroscopy (XANES) indicated that in both the biotically and abiotically generated calcites the Sr was incorporated into the calcite

  2. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts. ...

  3. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts. ...

  4. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts. ...

  5. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  6. 40 CFR 415.650 - Applicability; description of the cobalt salts production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... cobalt salts production subcategory. 415.650 Section 415.650 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Cobalt Salts Production Subcategory § 415.650 Applicability; description of the cobalt... cobalt salts....

  7. Cobalt-related defects in silicon

    NASA Astrophysics Data System (ADS)

    Gibbons, T. M.; Backlund, D. J.; Estreicher, S. K.

    2017-01-01

    Transition metals from the 3d series are unavoidable and unwanted contaminants in Si-based devices. Cobalt is one of the most poorly understood impurities with incomplete experimental information and few theoretical studies. In this contribution, the properties of interstitial cobalt (Coi) in Si and its interactions with the vacancy, self-interstitial, hydrogen, and substitutional boron are calculated using the first-principles tools. The stable configurations, gap levels, and binding energies are predicted. The activation energy for diffusing Coi is calculated with the nudged-elastic-band method and found to be slightly lower than that of interstitial copper and nickel. The binding energies and gap levels of the substitutional cobalt (Cos) and of the {Cos,H} and {Cos,H,H} complexes are close to the experimental data. The properties of the cobalt-boron pair are calculated.

  8. Bioextraction of cobalt from complex metal sulfides

    SciTech Connect

    Thompson, D.L.; Noah, K.S.; Wichlacz, P.L.; Torma, A.E.

    1993-05-01

    The present study has investigated the bioleachability of naturally occurring cobaltite and synthetic cobalt sulfides using 29 pedigree and ``wild type`` strains of Thiobacillus ferrooxidans. On the basis of a screening test, five strains of bacteria were selected for assessing the effects of leach parameters (pH, ferrous and ferric sulfates, ammonium sulfate, bipotassium hydrogen phosphate, and substrate concentrations) on cobalt extraction from Blackbird Mine ore and concentrate. The mechanisms of cobalt extraction were explained in terms of direct and indirect modes of bacterial activity, and the chemistry involved in these processes was identified. Using various size fractions of a high-grade cobaltite, the kinetic parameters of cobalt extraction were derived for the effect of specific surface area to be V{sub m} = 376 mg dm{sup {minus}3} h{sup {minus}1} and K 1.27 m{sup 2} g{sup {minus}1}.

  9. Bioextraction of cobalt from complex metal sulfides

    SciTech Connect

    Thompson, D.L.; Noah, K.S.; Wichlacz, P.L.; Torma, A.E.

    1993-01-01

    The present study has investigated the bioleachability of naturally occurring cobaltite and synthetic cobalt sulfides using 29 pedigree and wild type'' strains of Thiobacillus ferrooxidans. On the basis of a screening test, five strains of bacteria were selected for assessing the effects of leach parameters (pH, ferrous and ferric sulfates, ammonium sulfate, bipotassium hydrogen phosphate, and substrate concentrations) on cobalt extraction from Blackbird Mine ore and concentrate. The mechanisms of cobalt extraction were explained in terms of direct and indirect modes of bacterial activity, and the chemistry involved in these processes was identified. Using various size fractions of a high-grade cobaltite, the kinetic parameters of cobalt extraction were derived for the effect of specific surface area to be V[sub m] = 376 mg dm[sup [minus]3] h[sup [minus]1] and K 1.27 m[sup 2] g[sup [minus]1].

  10. Thermal oxidation of cobalt disilicide

    NASA Astrophysics Data System (ADS)

    Bartur, M.; Nicolet, M.-A.

    1982-10-01

    The thermal oxidation kinetics of cobalt disilicide on Si substrates have been investigated in the temperature range of 650 1100 °C in dry oxygen and wet oxygen. A surface layer of SiO2 grows parabolically with time. The growth rate is independent of the substrate orientation (<111> or <100>) and thickness of the CoSi2 layer. We surmize that the oxidation mechanism is dominated by the diffusion of an oxidant through the growing SiO2. Activation energies for the dry and wet oxidation are 1.49±0.05 eV and 1.05±0.05 eV, respectively. The kinetics is exactly the same as for NiSi2 oxidation which suggest that the same mechanism controls the oxidation of these two similar suicides.

  11. Translocation and incorporation of strontium carbonate derived strontium into calcium oxalate crystals by the wood decay fungus Resinicium bicolor

    Treesearch

    Jon H. Connolly; Walter C. Shortle; Jody Jellison

    1999-01-01

    The white-rot wood decay fungus Resinicium bicolor (Abertini & Schwein.: Fr.) Parmasto was studied for its ability to solubilize and translocate ions from the naturally occurring mineral strontianite. Resinicium bicolor colonized a soil mixture culture medium containing strontianite sand, solubilized strontium ions from this...

  12. Influence of several antidotal treatments on the distribution and excretion of strontium

    SciTech Connect

    Llobet, J.M.; Colomina, M.T.; Domingo, J.L. ); Corbella, J. )

    1992-01-01

    Eleven chelating agents were examined to determine their effectiveness on the removal of strontium in mice following s.c. injection of strontium nitrate. Chelators were administered i.p. at doses equal to one-fourth of their respective LD{sub 50}. Kryptofix 222 and DTPA were the most effective agents in increasing the urinary excretion of strontium and reducing the concentrations of strontium in various tissues. In a second series of experiments, tartaric acid, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), EGTA, DTPA and Kryptofix 222 were administered i.p. ten minutes after the s.c injection of strontium nitrate. At these levels of strontium, none of the chelators significantly enhanced the excretion of strontium or lowered the strontium tissue concentrations. Because the chelators tested were ineffective in removing strontium from the body, further investigations should be conducted to identify other chelating agents and conditions of administration which may significantly enhance the removal of strontium.

  13. Effect of strontium ranelate on bone mineral: Analysis of nanoscale compositional changes.

    PubMed

    Rossi, André L; Moldovan, Simona; Querido, William; Rossi, Alexandre; Werckmann, Jacques; Ersen, Ovidiu; Farina, Marcos

    2014-01-01

    Strontium ranelate has been used to prevent bone loss and stimulate bone regeneration. Although strontium may integrate into the bone crystal lattice, the chemical and structural modifications of the bone when strontium interacts with the mineral phase are not completely understood. The objective of this study was to evaluate apatite from the mandibles of rats treated with strontium ranelate in the drinking water and compare its characteristics with those from untreated rats and synthetic apatites with and without strontium. Electron energy loss near edge structures from phosphorus, carbon, calcium and strontium were obtained by electron energy loss spectroscopy in a transmission electron microscope. The strontium signal was detected in the biological and synthetic samples containing strontium. The relative quantification of carbon by analyzing the CK edge at an energy loss of ΔE = 284 eV showed an increase in the number of carbonate groups in the bone mineral of treated rats. A synthetic strontium-containing sample used as control did not exhibit a carbon signal. This study showed physicochemical modifications in the bone mineral at the nanoscale caused by the systemic administration of strontium ranelate.

  14. [Thyrotropic deficiency].

    PubMed

    Chanson, P

    1998-11-15

    Central hypothyroidism (thyrotropic deficiency) is due to a defect in TSH secretion by thyrotrophs (or alternatively to an altered bioactivity of TSH). Central hypothyroidism is rare and is often associated with other pituitary deficiencies as it is generally encountered in case of hypothalamo-pituitary tumoral process. Clinical symptoms are milder than those of primary thyroid failure. Diagnosis is based on free T4 measurement whose level is decreased while TSH concentration is normal or minimally increased, reflecting an alteration in the bioactivity of TSH. Replacement therapy is monitored by T4 level measurement: the objective is to obtain normal T4 levels. TSH concentration must not be taken into account for the adjustment of the thyroxine doses.

  15. Role of cobalt in nickel base superalloys

    NASA Technical Reports Server (NTRS)

    Jarrett, R.; Barefoot, J.; Tien, J.; Sanchez, J.

    1982-01-01

    The effect of cobalt or substituting for cobalt on the mechanical properties of nickel-based superalloys is discussed. Waspaloy, UDIMET 700, and NIMONIC 115, which are representative of Ni-Cr-Co-Al-Ti-Mo superalloys having different gamma prime contents which are strengthened by a heavily alloyed matrix, coherent gamma prime precipitates, and carbides at the grain boundaries. Microstructure and in situ and extracted phase STEM micro-analysis were used to evaluate the three alloys.

  16. Role of cobalt in nickel base superalloys

    NASA Technical Reports Server (NTRS)

    Jarrett, R.; Barefoot, J.; Tien, J.; Sanchez, J.

    1982-01-01

    The effect of cobalt or substituting for cobalt on the mechanical properties of nickel-based superalloys is discussed. Waspaloy, UDIMET 700, and NIMONIC 115, which are representative of Ni-Cr-Co-Al-Ti-Mo superalloys having different gamma prime contents which are strengthened by a heavily alloyed matrix, coherent gamma prime precipitates, and carbides at the grain boundaries. Microstructure and in situ and extracted phase STEM micro-analysis were used to evaluate the three alloys.

  17. Isolation of strontium pools and isotope ratios in modern human hair.

    PubMed

    Tipple, Brett J; Chau, Thuan; Chesson, Lesley A; Fernandez, Diego P; Ehleringer, James R

    2013-10-10

    The elements of human hair record specific information about an individual's health, diet, and surrounding environment. Strontium isotope ratios of human hair have attracted interest as they potentially record an individual's environment. Yet, separating the external environmental signals from the internal dietary indicators has remained a challenge. Here, we examined the effects of five different hair-cleaning methodologies to determine the extent that internal and external strontium signals can be isolated from human hair. In the first study of its kind, we employed an in-line strontium purification methodology and a multi-collector inductively coupled plasma mass spectrometer to obtain high-precision strontium isotope ratio of human hair and of leachates of the different washing treatments. We found that the different applications of an individual treatment removed a consistent amount of strontium from hair and that replicate analyses showed each treatment altered the strontium isotope ratios of hair consistently. A mass-balance approach was applied to demonstrate that strontium was quantitatively removed and was accounted for in either the treated hair or the leachate. We observed that strontium isotope ratio varied as a function of treatment aggressiveness so as to suggest that there was a fine-scale structuring of strontium within hair (transverse cross-sectional variations); these variations existed as differences in strontium concentrations and isotope ratios. As a result, the Sr isotope ratio of hair and hair leachates treated with the most aggressive cleaning methods reflected the isotope ratios of the interior and total exterior strontium signatures, respectively. The results of this study indicate that external environmental strontium signals can be distinguished from the internal signals and therefore permit the application of strontium isotope ratios of modern human hair for geospatial applications.

  18. Nickel acts as an adjuvant during cobalt sensitization.

    PubMed

    Bonefeld, Charlotte Menné; Nielsen, Morten Milek; Vennegaard, Marie T; Johansen, Jeanne Duus; Geisler, Carsten; Thyssen, Jacob P

    2015-03-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses in the draining lymph nodes compared to mice sensitized with cobalt alone. In contrast, the presence of cobalt during nickel sensitization only induced an increased CD8(+) T cell proliferation during challenge to nickel. Thus, the presence of nickel during cobalt sensitization potentiated the challenge response against cobalt more than the presence of cobalt during sensitization to nickel affected the challenge response against nickel. Taken together, our study demonstrates that sensitization with a mixture of nickel and cobalt leads to an increased immune response to both nickel and cobalt, especially to cobalt, and furthermore that the adjuvant effect appears to correlate with the inflammatory properties of the allergen. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Cobalt compounds as antidotes for hydrocyanic acid

    PubMed Central

    Evans, C. Lovatt

    1964-01-01

    The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5×LD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5×LD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3×LD50) than for mice (2×LD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered. PMID:14256807

  20. COBALT COMPOUNDS AS ANTIDOTES FOR HYDROCYANIC ACID.

    PubMed

    EVANS, C L

    1964-12-01

    The antidotal potency of a cobalt salt (acetate), of dicobalt edetate, of hydroxocobalamin and of cobinamide against hydrocyanic acid was examined mainly on mice and rabbits. All the compounds were active antidotes for up to twice the LD50; under some conditions for larger doses. The most successful was cobalt acetate for rabbits (5xLD50), which was effective at a molar cyanide/cobalt (CN/Co) ratio of 5, but had as a side-effect intense purgation. Hydroxocobalamin was irregular in action, but on the whole was most effective for mice (4.5xLD50 at a molar ratio of 1), and had no apparent side effects. Dicobalt edetate, at molar ratios of up to 2, was more effective for rabbits (3xLD50) than for mice (2xLD50), but had fewer side effects than cobalt acetate. The effect of thiosulphate was to augment the efficacy of dicobalt edetate and, in mice, that of hydroxocobalamin; but, apparently, in rabbits, to reduce that of hydroxocobalamin. Cobinamide, at a molar ratio of 1, was slightly more effective than hydroxocobalamin on rabbits and also less irregular in its action. Cobalt acetate by mouth was effective against orally administered hydrocyanic acid. The oxygen uptake of the body, reduced by cyanide, is rapidly reinstated when one of the cobalt antidotes has been successfully administered.

  1. [Are the cobalt hip prosthesis dangerous?].

    PubMed

    Mistretta, Virginie; Kurth, William; Charlier, Corinne

    The placement of a hip prosthesis is one of the most common orthopedic surgical procedures. Some implants contain metal and are therefore capable of releasing metal particles like cobalt in patients who wear metal prostheses. Cobalt can be responsible of local toxicity (including metallosis, hypersensitivity reaction, and benign tumor) or systemic toxicity (including cardiomyopathy, polycythemia, hypothyroidism, and neurological disorders). To monitor potential toxicity of metal hip prostheses, an annual monitoring of patients implanted is recommended and includes clinical examination, radiological examination and blood cobalt determination. The cobalt concentration in blood allows to estimate the risk of toxicity and to evaluate the performance of the implant. The currently recommended threshold value is equal to 7 µg of cobalt per liter of blood. Our study, conducted on 251 patients over a period of 4 years, has shown that the cobalt concentration average was 2.51 µg/l in blood, with 51 patients having a cobaltemia higher than the threshold of 7 µg/l. © 2016 médecine/sciences – Inserm.

  2. Intolerability of cobalt salt as erythropoietic agent.

    PubMed

    Ebert, Bastian; Jelkmann, Wolfgang

    2014-03-01

    Unfair athletes seek ways to stimulate erythropoiesis, because the mass of haemoglobin is a critical factor in aerobic sports. Here, the potential misuse of cobalt deserves special attention. Cobalt ions (Co(2+) ) stabilize the hypoxia-inducible transcription factors (HIFs) that increase the expression of the erythropoietin (Epo) gene. Co(2+) is orally active, easy to obtain, and inexpensive. However, its intake can bear risks to health. To elaborate this issue, a review of the pertinent literature was retrieved by a search with the keywords 'anaemia', 'cobalt', 'cobalt chloride', 'erythropoiesis', 'erythropoietin', 'Epo', 'side-effects' and 'treatment', amongst others. In earlier years, cobalt chloride was administered at daily doses of 25 to 300 mg for use as an anti-anaemic agent. Co(2+) therapy proved effective in stimulating erythropoiesis in both non-renal and renal anaemia, yet there were also serious medical adverse effects. The intake of inorganic cobalt can cause severe organ damage, concerning primarily the gastrointestinal tract, the thyroid, the heart and the sensory systems. These insights should keep athletes off taking Co(2+) to stimulate erythropoiesis.

  3. Acute Cobalt-Induced Lung Injury and the Role of Hypoxia-Inducible Factor 1α in Modulating Inflammation

    PubMed Central

    Saini, Yogesh; Greenwood, Krista K.; Merrill, Christian; Kim, Kyung Y.; Patial, Sonika; Parameswaran, Narayanan; Harkema, Jack R.; LaPres, John J.

    2010-01-01

    Air pollution is a critical factor in the development and exacerbation of pulmonary diseases. Ozone, automobile exhaust, cigarette smoke, and metallic dust are among the potentially harmful pollution components that are linked to disease progression. Transition metals, such as cobalt, have been identified at significant levels in air pollution. Cobalt exerts numerous biological effects, including mimicking hypoxia. Similar to hypoxia, cobalt exposure results in the stabilization of hypoxia-inducible factors (HIFs), a family of proteins that regulate the cellular response to oxygen deficit. HIFs also play an important role in innate immunity and inflammatory processes. To characterize the role of HIF1α, the most ubiquitously expressed HIF, in the early events during cobalt-induced lung inflammation, an inducible lung-specific HIF1α deletion model was employed. Control mice showed classical signs of metal-induced injury following cobalt exposure, including neutrophilic infiltration and induction of Th1 cytokines. In contrast, HIF1α-deficient mice exhibited pronounced eosinophil counts in bronchoalveolar lavage fluid and lung tissue complemented with Th2 cytokine induction. The timing of these results suggests that the loss of epithelial-derived HIF1α alters the lung's innate immune response and biases the tissue toward a Th2-mediated inflammation. PMID:20511350

  4. Charged metallopolymers as universal precursors for versatile cobalt materials

    SciTech Connect

    Zhang, Jiuyang; Yan, Yi; Chance, Michael W.; Chen, Jihua; Hayat, Jeffery; Ma, Shuguo; Tang, Chuanbing

    2013-10-16

    Here, inorganic metal-based materials have been widely utilized in catalytic chemistry, life sciences, and engineering.[1] Cobalt-related materials, including metallic cobalt,[2] cobalt oxide,[3] cobalt alloy,[4] and cobalt phosphide,[5] have been used in magnetic materials, aerospace engineering, and energy storage. With the development of modern nanoelectronic technology and the increasing demand for nanostructured materials,[6] the preparation of nanostructured inorganic cobalt-containing materials has become a crucial technological challenge.

  5. Dissolved strontium and calcium levels in the tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Steiner, Zvi; Sarkar, Amit; Turchyn, Alexandra

    2017-04-01

    Measurements of seawater alkalinity and dissolved calcium concentrations along oceanic transects are often used to calculate calcium carbonate precipitation and dissolution rates. Given that the distribution coefficient of strontium in CaCO3 varies greatly between different groups of organisms, adding precise measurements of dissolved strontium concentrations provides opportunities to also track relative contributions of these different groups to the regional CaCO3 cycle. However, there are several obstacles to this approach. These obstacles include unresolved systematic discrepancies between seawater calcium and alkalinity data, very large analytical noise around the calcium concentration measurements and the unconstrained role of acantharia (radiolarian precipitating SrSO4 skeletons) in the marine strontium cycle. During the first cruise of the second International Indian Ocean Expedition (IIOE-2) water samples were collected along 67°E from 9°N to 5°S to explore the dissolution rate of calcium carbonate in the water. The dissolution rate can be calculated by combining measurements of water column potential alkalinity with calcium and strontium concentrations measured by ICP-OES and calcium concentration measurements using isotope dilution thermal ionization mass spectrometry (ID-TIMS). CaCO3 mineral saturation state calculated using pH and total alkalinity suggests that along 67°E, the aragonite saturation horizon lays at depth of 500 m on both sides of the equator. Across the cruise transect, dissolved strontium concentrations increase by 2-3% along the thermocline suggesting rapid recycling of strontium rich phases. This is particularly evident just below the thermocline at 8-9°N and below 1000 m water depth, south of the equator. The deep, southern enrichment in strontium does not involve a change in the Sr/Ca ratio, suggesting that this strontium enrichment is related to CaCO3 dissolution. In contrast, in the intermediate waters of the northern part of

  6. The growth, dielectric and lattice dynamical properties of strontium titanate and barium strontium titanate thin films

    NASA Astrophysics Data System (ADS)

    Clark, Anna Maria

    Ferroelectric materials have become increasingly important in microelectronic applications, such as dynamic random access memory, ferroelectric random access memory, and tunable microwave devices. This requires the growth of high quality ferroelectric thin films, as well as fundamental understanding of their structural and dielectric properties, which often differ from those in respective bulk materials. The present thesis focuses on the investigation of the perovskite type ferroelectrics strontium titanate, SrTiO3 (STO) and barium strontium titanate, BaxSr1- xTiO3 (BST). Pulsed laser deposition is considered as one of the most advantageous methods for the growth of thin ferroelectric films, and was used to produce STO films of high quality for this thesis. Influence of several deposition conditions, such as type of substrate, deposition temperature and chemical treatments of the substrate were investigated to determine their effects on the structural and electrical properties of STO films and to optimize deposition process and improve film quality. The surface morphology of films was studied by atomic force microscopy. X-ray diffraction was used to study their crystalline structure. It is shown in this thesis that the substrate has a pronounced effect on the crystalline quality and surface morphology of the film. Temperature and electric field dependencies of dielectric constant and loss tangent in STO films were studied by low frequency electric measurements. Improvements of the measured dielectric properties are correlated to the film deposition parameters. Raman spectroscopy was used to characterize the film structure and study the lattice dynamics of the thin films. Raman spectra show the STO films grown on STO single crystal substrates have a structural phase transition near the phase transition temperature in bulk STO. The soft TO1 phonon, related to the ferroelectric state, was observed in the STO thin films. Raman results of the soft-mode study show a

  7. Determination of strontium and simultaneous determination of strontium oxide, magnesium oxide and calcium oxide content of Portland cement by derivative ratio spectrophotometry.

    PubMed

    Idriss, K A; Sedaira, H; Ahmed, S S

    2009-04-15

    A derivative spectrophotometric method has been developed for the determination of strontium in Portland cement. The method is applied successfully for the simultaneous determination of SrO, MgO and CaO. It is based on the use of Alizarin Complexone (AC) as a complexing agent and measurement of the derivative ratio spectra of the analytes. Interferences of manganese(II) and zinc(II) were eliminated by precipitation. The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The strontium complex formed at pH 9.5 allows precise and accurate determination of strontium over the concentration range of 1.5-18 mg L(-1) of strontium. The MDL (at 95% confidence level) was found to be 25 ng mL(-1) for strontium in National Institute of Standards and Technology (NIST) cement samples using the proposed method.

  8. Biological responses of isolated macrophages to cobalt metal and tungsten carbide-cobalt powders.

    PubMed

    Lison, D; Lauwerys, R

    1991-10-01

    A previous study from this laboratory, using morphological and biochemical (LDH release) parameters, has shown that tungsten carbide-cobalt dust exhibits a greater cytotoxicity toward isolated macrophages than cobalt metal powder alone. The present study extends this comparison by examining additional biological parameters. Glucose uptake and superoxide anion production by isolated macrophages were significantly more depressed by the tungsten carbide-cobalt mixture (WC-Co) than by cobalt alone (Co) while pure tungsten carbide (WC) had no effect or even stimulated the cells. For glucose-6-phosphate dehydrogenase and cell-associated plasminogen activator (PA) activities, no difference between Co and WC-Co dusts was observed. These observations add further evidence to our previous findings regarding the different biological reactivity of cobalt metal alone or mixed with tungsten carbide.

  9. Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

    NASA Astrophysics Data System (ADS)

    Qi, B.; Andrew, J. S.; Arnold, D. P.

    2017-03-01

    This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain ( 100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe66Co34) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe2O4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

  10. Synergetic interactions improve cobalt leaching from lithium cobalt oxide in microbial fuel cells.

    PubMed

    Huang, Liping; Li, Tianchi; Liu, Chuan; Quan, Xie; Chen, Lijie; Wang, Aijie; Chen, Guohua

    2013-01-01

    Cobalt leaching from lithium cobalt oxide is a promising reduction process for recovery of cobalt and recycle of spent lithium ion batteries, but suffers from consumption of large amount of reductants and energy, and generation of excess secondary polluted sludge. Thus, effective and environmental friendly processes are needed to improve the existing process limitations. Here we reported microbial fuel cells (MFCs) to effectively reduce Co(III) in lithium cobalt oxide with concomitant energy generation. There was a synergetic interaction in MFCs, leading to a more rapid Co(III) leaching at a rate 3.4 times the sum of rates by conventional chemical processes and no-acid controls. External resistor, solid/liquid ratio, solution conductivity, pH and temperature affected system performance. This study provides a new process for recovery of cobalt and recycle of spent lithium ion batteries with concomitant energy generation from MFCs.

  11. Plasminogen deficiency.

    PubMed

    Celkan, Tiraje

    2017-01-01

    Plasminogen plays an important role in fibrinolysis as well as wound healing, cell migration, tissue modeling and angiogenesis. Congenital plasminogen deficiency is a rare autosomal recessive disorder that leads to the development of thick, wood-like pseudomembranes on mucosal surfaces, mostly seen in conjunctivas named as ''ligneous conjunctivitis''. Local conjunctival use of fresh frozen plazma (FFP) in combination with other eye medications such as cyclosporin and artificial tear drops may relieve the symptoms. Topical treatment with plasminogen eye drops is the most promising treatment that is not yet available in Turkey.

  12. Application of XRF to measure strontium in human bone in vivo

    SciTech Connect

    Wielopolski, L.; Vartsky, D.; Yasumura, S.; Cohn, S.H.

    1982-01-01

    As a basis for better understanding the role that Sr fulfills in human body, it is desirable to measure directly the main Sr store in human body. Although strontium is omnipresent in human tissues, 99% is stored inthe mineral portion of the bone. In the present study x-ray fluorescence (XRF) was applied to measure the strontium content of the tibial shaft in vivo. The feasibility studies showed that normal levels of stable strontium in the bone can be measured successfully.

  13. Characteristics of polyaniline cobalt supported catalysts for epoxidation reactions.

    PubMed

    Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

    2014-01-01

    A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established.

  14. Characteristics of Polyaniline Cobalt Supported Catalysts for Epoxidation Reactions

    PubMed Central

    Kowalski, Grzegorz; Pielichowski, Jan; Grzesik, Mirosław

    2014-01-01

    A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following acetonitrile/acetic acid solution or acetonitrile and then acetic acid solution. Moreover different ratios of Co(II) : PANI were studied. Catalysts obtained with both methods and at all ratios were investigated using various techniques including AAS and XPS spectroscopy. The optimum conditions for preparation of PANI/Co catalysts were established. Catalytic activity of polyaniline cobalt(II) supported catalysts was tested in dec-1-ene epoxidation with molecular oxygen at room temperature. The relationship between the amount of cobalt species, measured with both AAS and XPS techniques, and the activity of PANI-Co catalysts has been established. PMID:24701183

  15. Cobalt: A vital element in the aircraft engine industry

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1981-01-01

    Recent trends in the United States consumption of cobalt indicate that superalloys for aircraft engine manufacture require increasing amounts of this strategic element. Superalloys consume a lion's share of total U.S. cobalt usage which was about 16 million pounds in 1980. In excess of 90 percent of the cobalt used in this country was imported, principally from the African countries of Zaire and Zambia. Early studies on the roles of cobalt as an alloying element in high temperature alloys concentrated on the simple Ni-Cr and Nimonic alloy series. The role of cobalt in current complex nickel base superalloys is not well defined and indeed, the need for the high concentration of cobalt in widely used nickel base superalloys is not firmly established. The current cobalt situation is reviewed as it applies to superalloys and the opportunities for research to reduce the consumption of cobalt in the aircraft engine industry are described.

  16. Isotopic composition of strontium in sea water throughout Phanerozoic time

    USGS Publications Warehouse

    Peterman, Z.E.; Hedge, C.E.; Tourtelot, H.A.

    1970-01-01

    Isotopic analyses of strontium in primary fossil carbonate reveal significant variations in Sr87 Sr86 of sea water during the Phanerozoic. The strontium isotopic composition may have been uniform from the Ordovician through the Mississippian, with an average Sr87 Sr86 of 0.7078. A subsequent decrease in this value into the Mesozoic is interrupted by two provisionally documented positive pulses in Sr87 Sr86-one in the Early Pennsylvanian and one in the Early Triassic. The lowest observed value (0.7068) occurred in Late Jurassic time, and this was followed by a gradual increase to 0.7075 in the Late Cretaceous and a more rapid increase through the Tertiary to 0.7090 for modern sea water. These variations are thought to be the result of a complex interplay of periods of intense volcanism and epeirogenic movements of the continents on a worldwide scale. ?? 1970.

  17. Studies of Inhibition of Intestinal Absorption of Radioactive Strontium

    PubMed Central

    Skoryna, Stanley C.; Paul, T. M.; Waldron-Edward, Deirdre

    1965-01-01

    A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, allowing calcium to be available to the body. Studies were carried out on the inhibitory effect of various amounts of sodium alginate and the dose-response relationship of Sr89 and bone uptake. The results obtained indicated that under laboratory conditions sodium alginate effectively reduces Sr89 uptake in a constant proportion. This effect was observed at the three levels of administration of 1.4%, 12% and 24% of sodium alginate. The linear relationship between the dosage of the radioisotope and the bone uptake in the presence of sodium alginate suggests that the same proportion is maintained at the lower levels of intake of radioactive strontium. Previous studies with small constant doses of sodium alginate were extended in rats to a period corresponding approximately to three years of human life span. Low doses were sufficient to reduce appreciably bone uptake of radiostrontium. PMID:14341649

  18. New Approaches for Producing Quantum Degenerate Gases of Strontium

    NASA Astrophysics Data System (ADS)

    Ding, Roger; Woehl, Germano, Jr.; Camargo, Francisco; Whalen, Joseph; Dunning, F. Barry; Killian, Thomas

    2015-05-01

    We investigate two novel methods for laser cooling strontium to quantum degeneracy. The first takes advantage of the isotope shifts and the narrow 1S0 -3P1 intercombination line (7.5 kHz at 689 nm) to produce an isotope selective optical dipole trap (ODT). We demonstrate this technique by sympathetically cooling 88Sr or 87Sr using 86Sr to produce quantum degenerate gases. The second uses an acousto-optic modulator driven with multiple RF frequencies to dynamically shape a far-off resonance ODT. This is easy to implement in existing traps and allows for optimized loading and evaporation tailored for each isotope. The simple setup has been applied in various atomic physics experiments, and we describe its application in strontium. Research supported by the AFOSR under grant no. FA9550-12-1-0267, the NSF under grants nos. 1301773 and 1205946, and the Robert A. Welch Foundation under grant no. C-0734.

  19. Equilibrium Strontium Isotope Fractionation in Minerals and Solution

    NASA Astrophysics Data System (ADS)

    Schauble, E. A.; Griffith, E. M.

    2011-12-01

    Recent interest in stable strontium isotope fractionation highlights our lack of understanding of the processes separating the isotopes of heavy elements in nature. Here we present thermodynamic calculations of equilibrium strontium isotope (88Sr/86Sr) fractionation in minerals and aqueous solution (by analogy to crystalline strontium hydrates). Strontium is among the ten most abundant dissolved ions seawater, and is unique in this group because it encompasses an extensively studied, long-lived radiogenic tracer (87Sr/86Sr) as well as three stable isotopes. Strontium is also widely distributed as a trace element in sedimentary minerals (especially carbonates and sulfates) and more broadly as a substituent for the major elements calcium, sodium and/or potassium in high-temperature igneous and metamorphic assemblages. However, we are aware of only a few theoretical or experimental studies of fractionation of strontium isotopes in crystals or solution (1). An important goal of our work is to provide a baseline for determining whether equilibrium isotope partitioning is important for generating observed signatures, which can be particularly difficult to establish experimentally in solid materials at ambient temperatures. Mass dependent fractionations are estimated for stoichiometric strontium-bearing crystals, including strontianite (SrCO3), celestine (SrSO4), strontia (SrO), and strontiofluorite (SrF2), as well as crystals with hydrated Sr2+-ions (e.g., SrCl2.6H2O, which contains a [Sr(H2O)9]2+ substructure) and strontium-substituted barite (Sr:BaSO4). Calculations are based on density functional perturbation theory models of the vibrational (phonon) densities of states of 86Sr- and 88Sr-substituted crystals. Most of the models of celestine indicate instability in the known orthorhombic structure - possibly because of shortcomings in pseudopotentials or density functionals. The models predict that fractionations between crystals tend to be small; strontia

  20. Seawater strontium isotopes, acid rain, and the Cretaceous-Tertiary boundary

    NASA Technical Reports Server (NTRS)

    Macdougall, J. D.

    1988-01-01

    A large bolide impact at the end of the Cretaceous would have produced significant amounts of nitrogen oxides by shock heating of the atmosphere. The resulting acid precipitation would have increased continental weathering greatly and could be an explanation for the observed high ratio of strontium-87 to strontium-86 in seawater at about this time, due to the dissolution of large amounts of strontium from the continental crust. Spikes to high values in the seawater strontium isotope record at other times may reflect similar episodes.

  1. Strontium eluting graphene hybrid nanoparticles augment osteogenesis in a 3D tissue scaffold

    NASA Astrophysics Data System (ADS)

    Kumar, Sachin; Chatterjee, Kaushik

    2015-01-01

    The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium particles. Thermal gravimetric analysis further confirmed the composition of the hybrid particles as 22 wt% of strontium. Macroporous tissue scaffolds were prepared by incorporating RGO_Sr particles in poly(ε-caprolactone) (PCL). The PCL/RGO_Sr scaffolds were found to elute strontium ions in aqueous medium. Osteoblast proliferation and differentiation was significantly higher in the PCL scaffolds containing the RGO_Sr particles in contrast to neat PCL and PCL/RGO scaffolds. The increased biological activity can be attributed to the release of strontium ions from the hybrid nanoparticles. This study demonstrates that composites prepared using hybrid nanoparticles that elute strontium ions can be used to prepare multifunctional scaffolds with good mechanical and osteoinductive properties. These findings have important implications for designing the next generation of biomaterials for use in tissue regeneration.The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium

  2. Extraction of cesium and strontium from nuclear waste

    DOEpatents

    Davis, M.W. Jr.; Bowers, C.B. Jr.

    1988-06-07

    Cesium is extracted from acidified nuclear waste by contacting the waste with a bis 4,4[prime](5) [1-hydroxy-2-ethylhexyl]benzo 18-crown-6 compound and a cation exchanger in a matrix solution. Strontium is extracted from acidified nuclear waste by contacting the waste with a bis 4,4[prime](5[prime]) [1-hydroxyheptyl]cyclohexo 18-crown-6 compound, and a cation exchanger in a matrix solution. 3 figs.

  3. Extraction of cesium and strontium from nuclear waste

    DOEpatents

    Davis, Jr., Milton W.; Bowers, Jr., Charles B.

    1988-01-01

    Cesium is extracted from acidified nuclear waste by contacting the waste with a bis 4,4'(5) [1-hydroxy-2-ethylhexyl]benzo 18-crown-6 compound and a cation exchanger in a matrix solution. Strontium is extracted from acidified nuclear waste by contacting the waste with a bis 4,4'(5') [1-hydroxyheptyl]cyclohexo 18-crown-6 compound, and a cation exchanger in a matrix solution.

  4. Vibrational spectra of the two hydrates of strontium oxalate.

    PubMed

    D'Antonio, Maria C; Torres, María M; Palacios, Daniel; González-Baró, Ana C; Baran, Enrique J

    2015-02-25

    The infrared and Raman spectra of the two hydrates of strontium oxalate, SrC2O4⋅H2O and SrC2O4⋅2H2O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the related calcium oxalates and other previously investigated metallic oxalates. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. P-type conductivity in annealed strontium titanate

    DOE PAGES

    Poole, Violet M.; Corolewski, Caleb D.; McCluskey, Matthew D.

    2015-12-17

    In this study, Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO3, or STO) samples that were annealed at 1200°C. Room temperature mobilities above 100 cm2/Vs were measured, an order of magnitude higher than those for electrons (5-10 cm2/Vs). Average hole densities were in the 109-1010 cm-3 range, consistent with a deep acceptor.

  6. Effects of strontium ranelate on spinal osteoarthritis progression.

    PubMed

    Bruyere, O; Delferriere, D; Roux, C; Wark, J D; Spector, T; Devogelaer, J-P; Brixen, K; Adami, S; Fechtenbaum, J; Kolta, S; Reginster, J-Y

    2008-03-01

    The aim of this study was to determine whether a 3-year treatment with strontium ranelate could delay the progression of spinal osteoarthritis (OA). This study was a post-hoc analysis of pooled data from the Spinal Osteoporosis Therapeutic Intervention (SOTI) and TReatment Of Peripheral OSteoporosis (TROPOS) trials performed on 1105 women with osteoporosis and concomitant radiological spinal OA at baseline, and for whom lumbar x-rays were available at baseline and over the 3-year treatment period. The presence and severity of osteophytes, disc space narrowing and sclerosis in the lumbar intervertebral spaces was graded according to a validated method, and an overall OA score was calculated for each intervertebral space. Back pain (measured on a five-point Likert scale only in SOTI) and health-related quality of life (SF-36 questionnaire) were assessed at baseline and after 3 years. Patients who suffered an incident or progressive vertebral fracture during the study were excluded from the analysis. The proportion of patients with worsening overall spinal OA score was reduced by 42% in the strontium ranelate group, compared with placebo (RR, 0.58; 95% CI, 0.42 to 0.79; p = 0.0005). Significantly more patients in the strontium ranelate group experienced an improvement in back pain after 3 years, compared with placebo (p = 0.03), while no significant difference was observed in terms of health-related quality of life between these patient groups. The results of this post-hoc analysis suggest that strontium ranelate could reduce the progression of the radiographic features of spinal OA and back pain in women with osteoporosis and prevalent spinal OA.

  7. Complex Impedance Studies of Optically Excited Strontium Barium Niobate

    DTIC Science & Technology

    2007-11-02

    has a tetragonal tungsten - bronze structure. The unit cell for this structure, illustrated below in Fig. 2.1, consists of ten oxygen octahedra joined...4 Kittel, pp. 373-374. 5 P. B. Jamieson, et al, “Ferroelectric Tungsten Bronze -Type Crystal Structures. I. Barium Strontium Niobate...Oxford, 1987). 2. C. Kittel, Introduction to Solid State Physics, (Wiley, New York, 1986). 3. P. B. Jamieson, et al, “Ferroelectric Tungsten

  8. Treatment of metastatic bone pain with strontium-89.

    PubMed

    Robinson, R G; Spicer, J A; Preston, D F; Wegst, A V; Martin, N L

    1987-01-01

    We have utilized 89Sr as palliative treatment for bone pain secondary to metastatic cancer in the skeleton of over 200 patients. The best results have been in patients with carcinoma of the prostate (80% response rate) and breast (89%). Results in a small number of patients with a variety of other cell types were not nearly as encouraging. Strontium-89 provides excellent palliation in the management of bone pain secondary to prostate and breast carcinoma.

  9. Synthesis of Samarium Cobalt Nanoblades

    SciTech Connect

    Darren M. Steele

    2010-08-25

    As new portable particle acceleration technologies become feasible the need for small high performance permanent magnets becomes critical. With particle accelerating cavities of a few microns, the photonic crystal fiber (PCF) candidate demands magnets of comparable size. To address this need, samarium cobalt (SmCo) nanoblades were attempted to be synthesized using the polyol process. Since it is preferable to have blades of 1-2 {micro}m in length, key parameters affecting size and morphology including method of stirring, reaction temperature, reaction time and addition of hydroxide were examined. Nanoparticles consisting of 70-200 nm spherical clusters with a 3-5 nm polyvinylpyrrolidone (PVP) coating were synthesized at 285 C and found to be ferromagnetic. Nanoblades of 25nm in length were observed at the surface of the nanoclusters and appeared to suggest agglomeration was occurring even with PVP employed. Morphology and size were characterized using a transmission electron microscope (TEM). Powder X-Ray Diffraction (XRD) analysis was conducted to determine composition but no supportive evidence for any particular SmCo phase has yet been observed.

  10. Strontium isotope ratios and the origin of anorthosites

    SciTech Connect

    Vinogradov, V.I.

    1986-01-01

    Anorthosites are rocks consisting almost completely of calcic plagioclase, usually from andesine to labradorite. They are not widespread, and until recently were of no economic interest. However, with the advance of the new global tectonics, which has excited considerable interest in the structure and composition of upper-mantle rocks, interest in the anorthosites has grown. This has particularly been the case since the discovery of anorthosites on the moon, where they appear to be more widespread than on the earth. Data have recently been obtained on the strontium isotope compositions of anorthosite intrusions in the Dzhugdzhur-Stanovoy zone and in the rocks surrounding them, which have revealed some unexpected features. The paper describes the geological features of anorthosites, initial concepts on strontium isotope geochemistry, strontium isotope compositions of this region, and discusses some genetic consequences from the isotope data. Although the data of this study are insufficient to determine the origin of anorthosites, the data indicate several points which should be considered in following studies. 11 references, 1 figure.

  11. Strontium borate glass: potential biomaterial for bone regeneration.

    PubMed

    Pan, H B; Zhao, X L; Zhang, X; Zhang, K B; Li, L C; Li, Z Y; Lam, W M; Lu, W W; Wang, D P; Huang, W H; Lin, K L; Chang, J

    2010-07-06

    Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones.

  12. Assessment of strontium in the Savannah River Site environment

    SciTech Connect

    Carlton, W.H.; Evans, A.G.; Geary, L.A.; Murphy, C.E. Jr.; Strom, R.N.

    1992-12-31

    This document on strontium is published as a part of the Radiological Assessment Program (RAP). It is the sixth in a series of eight documents on individual radioisotopes released to the environment as a result of SRS (Savannah River Site) operations. Strontium exists in the environment as a result of above-ground nuclear weapons tests, the Chernobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operation of industrial, medical, and educational facilities. Strontium has been produced at SRS during the operation of 5 production reactors. About 300 curies of radiostrontium were released into streams in the late 50s and 60s, primarily from leaking fuel elements in reactor storage basins. Smaller quantities were released from the fuel reprocessing operations. About 400 Ci were released to seepage basins. A much smaller quantity, about 2 Ci, was released to the atmosphere. The overall radiological impact of SRS releases on the offsite maximum individual can be characterized by total doses of 6.2 mrem (atmospheric) and 1.4 mrem (liquid), compared with a dose of 12,960 mrem from non-SRS sources during the same period of time. Radiostrontium releases have resulted in a negligible risk to the environment and the population it supports.

  13. The diffusion of cesium, strontium, and europium in silicon carbide

    NASA Astrophysics Data System (ADS)

    Dwaraknath, S. S.; Was, G. S.

    2016-08-01

    A novel multi-layer diffusion couple was used to isolate the diffusion of strontium, europium and cesium in SiC without introducing radiation damage to SiC and at concentrations below the solubility limit for the fission products in SiC. Diffusion occurred by both bulk and grain boundary pathways for all three fission products between 900∘ C and 1 ,300∘ C. Cesium was the fastest diffuser below 1 ,100∘ C and the slowest above this temperature. Strontium and europium diffusion tracked very closely as a function of temperature for both bulk and grain boundary diffusion. Migration energies ranged from 1.0 eV to 5.7 eV for bulk diffusion and between 2.2 eV and 4.7 eV for grain boundary diffusion. These constitute the first measurements of diffusion of cesium, europium, and strontium in silicon carbide, and the magnitude of the cesium diffusion coefficient supports the premise that high quality TRISO fuel should have minimal cesium release.

  14. TRPV3 channels mediate strontium-induced mouse egg activation

    PubMed Central

    Carvacho, Ingrid; Lee, Hoi Chang; Fissore, Rafael A.; Clapham, David E.

    2014-01-01

    SUMMARY In mammals, calcium influx is required for oocyte maturation and egg activation. The molecular identities of the calcium-permeant channels that underlie the initiation of embryonic development are not established. Here, we describe a Transient Receptor Potential (TRP) ion channel current activated by TRP agonists that is absent in TrpV3−/− eggs. TRPV3 current is differentially expressed during oocyte maturation, reaching a peak of maximum density and activity at metaphase of meiosis II (MII), the stage of fertilization. Selective activation of TRPV3 channels provokes egg activation by mediating massive calcium entry. Widely used to activate eggs, strontium application is known to yield normal offspring in combination with somatic cell nuclear transfer. We show that TRPV3 is required for strontium influx, as TrpV3−/− eggs failed to permeate Sr2+ or undergo strontium-induced activation. We propose that TRPV3 is the major mediator of calcium influx in mouse eggs and is a putative target for artificial egg activation. PMID:24316078

  15. Studies on Inhibition of Intestinal Absorption of Radioactive Strontium

    PubMed Central

    Paul, T. M.; Edward, Deirdre Waldron; Skoryna, Stanley C.

    1964-01-01

    A method is reported that enables selective suppression of absorption of radioactive strontium from ingested food material, permitting calcium to remain available to the body. Studies were carried out by measuring blood levels and bone uptake of Sr89 and Ca45 at different time intervals after orogastric intubation of rats. The addition of sodium alginate, derived from brown marine algae, to the radioactive isotopes increased the overall physiological discrimination against strontium by amounts up to 60% after 24 hours. This discrimination was further increased by feeding sodium alginate mixed with standard diet in the proportions of 20:80 and 30:70. The observed ratio was reduced by administration of sodium alginate from 0.25 to 0.09. Determination of the limiting dosage in rats is restricted to the amounts which rats will consume. In the event of an inadvertent release of radioactive strontium, human subjects probably could increase their intake of alginate at will, permitting a greater effectiveness of sodium alginate than could be obtained in experimental animals. PMID:14176062

  16. Pulsed laser deposition of strontium-substituted hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Pereiro, I.; Rodríguez-Valencia, C.; Serra, C.; Solla, E. L.; Serra, J.; González, P.

    2012-09-01

    The growing evidence of the beneficial role of strontium in bone has increased the interest of developing strontium-containing biomaterials for medical applications, and specifically biocompatible coatings that can be deposited on metallic implants to benefit from their load-bearing capabilities. In this work, strontium-substituted hydroxyapatite (Sr-HA) coatings have been fabricated by pulsed laser deposition (PLD) from initial targets obtained after mixing and compacting commercial HA and SrCO3 powders in different proportions. The films thus fabricated were then structurally, morphologically and chemically characterized using scanning electron microscopy, optical profilometry, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The macroscopic morphology of the films presented in all cases equivalent spherical shaped aggregates of typical calcium phosphate coatings. The results reveal, however, the incorporation of Sr2+ and carbonate groups in the coatings as a function of the SrCO3 content in the ablation target, being the incorporation of Sr2+ a linear phenomenon that is accompanied by a similarly linear withdrawal of Ca2+. The role of Sr2+ in the modification of the HA structure and a possible mechanism of substitution of Sr2+ atoms in place of Ca2+ atoms are discussed.

  17. Strontium borate glass: potential biomaterial for bone regeneration

    PubMed Central

    Pan, H. B.; Zhao, X. L.; Zhang, X.; Zhang, K. B.; Li, L. C.; Li, Z. Y.; Lam, W. M.; Lu, W. W.; Wang, D. P.; Huang, W. H.; Lin, K. L.; Chang, J.

    2010-01-01

    Boron plays important roles in many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the delivery of boron by the degradation of borate glass is of special interest in biomedical applications. However, the cytotoxicity of borate glass which arises with the rapid release of boron has to be carefully considered. In this study, it was found that the incorporation of strontium into borate glass can not only moderate the rapid release of boron, but also induce the adhesion of osteoblast-like cells, SaOS-2, thus significantly increasing the cyto-compatibility of borate glass. The formation of multilayers of apatite with porous structure indicates that complete degradation is optimistic, and the spread of SaOS-2 covered by apatite to form a sandwich structure may induce bone-like tissue formation at earlier stages. Therefore, such novel strontium-incorporated borosilicate may act as a new generation of biomaterial for bone regeneration, which not only renders boron as a nutritious element for bone health, but also delivers strontium to stimulate formation of new bones. PMID:20031984

  18. Production of very-high-n strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Ye, S.; Zhang, X.; Killian, T. C.; Dunning, F. B.; Hiller, M.; Yoshida, S.; Nagele, S.; Burgdörfer, J.

    2013-10-01

    The production of very-high-n (n˜300-500) strontium Rydberg atoms is explored using a crossed-laser-atom-beam geometry. n1S0 and n1D2 states are created by two-photon excitation via the 5s5p 1P1 intermediate state using radiation with wavelengths of ˜461 and ˜413 nm. Rydberg atom densities as high as ˜3×105 cm-3 have been achieved, sufficient that Rydberg-Rydberg interactions can become important. The isotope shifts in the Rydberg series limits are determined by tuning the 461-nm light to preferentially excite the different strontium isotopes. Photoexcitation in the presence of an applied electric field is examined. The initially quadratic Stark shift of the n1P1 and n1D2 states becomes near-linear at higher fields and the possible use of n1D2 states to create strongly polarized, quasi-one-dimensional electronic states in strontium is discussed. The data are analyzed with the aid of a two-active-electron (TAE) approximation. The two-electron Hamiltonian, within which the Sr2+ core is represented by a semi-empirical potential, is numerically diagonalized allowing the calculation of the energies of high-n Rydberg states and their photoexcitation probabilities.

  19. Structural analysis of a series of strontium-substituted apatites.

    PubMed

    O'Donnell, M D; Fredholm, Y; de Rouffignac, A; Hill, R G

    2008-09-01

    A series of Sr-substituted hydroxyapatites, (Sr(x)Ca(1-)(x))(5)(PO(4))(3)OH, where x=0.00, 0.25, 0.50, 0.75 and 1.00, were made by a standard wet chemical route and investigated using X-ray diffraction (XRD), Rietveld refinement and Raman spectroscopy. We report apatites manufactured by two synthesis routes under 90 degrees C, and only the fully Sr-substituted sample had a small amount of an impurity phase, which is believed to be strontium pyrophosphate. Lattice parameters (a and c), unit cell volume and density were shown to increase linearly with strontium addition and were consistent with the addition of a slightly larger and heavier ion (Sr) in place of Ca. XRD Lorentzian peak widths increased to a maximum at x=0.50, then decreased with increasing Sr content. This indicated an increase in crystallite size when moving away from the x=0.50 composition (d approximately 9.4nm). There was a slight preference for strontium to enter the Ca(II) site in the mixed apatites (6 to 12% depending on composition). The position of the Raman band attributed to v(1)PO(4)(3-) at around 963cm(-1) in hydroxyapatite decreased linearly to 949cm(-1) at full Sr-substitution. The full width at half maximum of this peak also correlated well and increased linearly with increasing crystallite size calculated from XRD.

  20. Lifetimes of ultra-long-range strontium Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Camargo, F.; Whalen, J. Â. D.; Ding, R.; Sadeghpour, H. R.; Yoshida, S.; Burgdörfer, J.; Dunning, F. B.; Killian, T. C.

    2016-02-01

    The lifetimes of the lower-lying vibrational states of ultra-long-range strontium Rydberg molecules comprising one ground-state 5 s2 1S0 atom and one Rydberg atom in the 5 s 38 s 3S1 state are reported. The molecules are created in an ultracold gas held in an optical dipole trap and their numbers determined using field ionization, the product electrons being detected by a microchannel plate. The measurements show that, in marked contrast to earlier measurements involving rubidium Rydberg molecules, the lifetimes of the low-lying molecular vibrational states are very similar to those of the parent Rydberg atoms. This results because the strong p -wave resonance in low-energy electron-rubidium scattering, which strongly influences the rubidium molecular lifetimes, is not present for strontium. The absence of this resonance offers advantages for experiments involving strontium Rydberg atoms as impurities in quantum gases and for testing of theories of molecular formation and decay.

  1. Lifetimes of ultra-long-range strontium Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Camargo, F.; Whalen, J. D.; Ding, R.; Sadeghpour, H. R.; Yoshida, S.; Burgdorfer, J.; Dunning, F. B.; Killian, T. C.

    2016-05-01

    The lifetimes of the lower-lying vibrational states of ultralong-range strontium Rydberg molecules comprising one ground-state 5s2 1S0 atom and one Rydberg atom in the 5s 38s3S1 state are reported. The molecules are created in an ultracold gas held in an optical dipole trap and their numbers determined using field ionization, the product electrons being detected by a microchannel plate. The measurements show that, in marked contrast to earlier measurements involving rubidium Rydberg molecules, the lifetimes of the low-lying molecular vibrational states are very similar to those of the parent Rydberg atoms. This results because the strong p-wave resonance in low-energy electron-rubidium scattering, which strongly influences the rubidium molecular lifetimes, is not present for strontium. The absence of this resonance offers advantages for experiments involving strontium Rydberg atoms as impurities in quantum gases and for testing theories of molecular formation and decay. This research was supported by the AFOSR, NSF, the Robert A. Welch Foundation, the FWF (Austria), FWF-SFB049 NextLite. H.R.S. was supported by a Grant to ITAMP from the NSF.

  2. Nickel, cobalt and chromate sensitization and occupation.

    PubMed

    Rui, Francesca; Bovenzi, Massimo; Prodi, Andrea; Fortina, Anna Belloni; Romano, Ilaria; Peserico, Andrea; Corradin, Maria Teresa; Carrabba, Enrico; Filon, Francesca Larese

    2010-04-01

    Exposure to nickel, cobalt and chromate are important causes of occupational contact dermatitis. To estimate the prevalence of nickel, cobalt and chromate allergy in a population of consecutive patients and to investigate the possible association with individual and occupational risk factors. A total of 14 464 patients (67.6% women and 32.4% men) with suspected allergic dermatitis underwent patch tests. The associations between patch test results and occupations were studied by multivariate logistic regression analysis. About 24.6% of the patients reacted positively to nickel sulphate, 10.2% to cobalt chloride and 8.7% to potassium dichromate. Nickel sensitization was higher in women aged 26-35 years in comparison with the youngest group (15-25 years) and the older group (> 45 years). In women, the prevalence of positive reactions to nickel was positively associated with metal and mechanical work (OR 1.54; 95%, CI 1.16-2.05). Chromate sensitization was more prevalent in building trade workers for both women (OR 1.58; 95% CI 1.00-2.49) and men (OR 2.24; 95% CI 1.55-3.22). Cobalt sensitization was associated with textile and leather work in women (OR 1.52; 95% CI 1.09-2.12) and with cleaning work in men (OR 1.86; 95% CI 1.18-2.93). Our study showed interesting associations between some occupations and nickel, chromate and cobalt allergy.

  3. Equilibrium phase boundary between hcp-cobalt and fcc-cobalt

    NASA Astrophysics Data System (ADS)

    Cynn, Hyunchae; Lipp, Magnus J.; Evans, William J.; Baer, Bruce J.

    In 2000 (Yoo et al., PRL), fcc-cobalt was reported as a new high pressure phase transforming from ambient hcp-cobalt starting at around 105 GPa and 300 K. Both cobalts coexist up to 150 GPa and thereafter only fcc-cobalt was found to be the only stable phase to 200 GPa. Our recent synchrotron x-ray diffraction data on cobalt are at odds with the previous interpretation. We will present our new finding and elaborate on our understanding in terms of the equilibrium phase boundary of cobalt. We will also compare our previous work on xenon (Cynn et al., 2001, PRL) with our new results on cobalt. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Portions of this work were performed at HPCAT (Sector 16), APS, Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA under Award No. DENA0001974 and DOE-BES under Award No. DE-FG02-99ER45775. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

  4. Palladium-cobalt particles as oxygen-reduction electrocatalysts

    DOEpatents

    Adzic, Radoslav; Huang, Tao

    2009-12-15

    The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

  5. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

  6. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

  7. 40 CFR 721.10201 - Cobalt lithium manganese nickel oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cobalt lithium manganese nickel oxide... Specific Chemical Substances § 721.10201 Cobalt lithium manganese nickel oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as cobalt lithium manganese...

  8. [Suppression of activity of Candida albicans proteinases by cobalt chloride].

    PubMed

    Kutyreva, M P; Mukhametzianova, A R; Ulakhovich, N A

    2012-01-01

    Influence of cobalt (II) chloride on the system of Candida albicans proteinase (SAP C. alb.) (both in solution and immobilized on a surface of nitrocellulose membranes) has been investigated. In solution cobalt chloride inactivated inducible but not constitute enzyme. In the heterogenous sytem proteolitical effect of the cobalt ion on inductible proteinase was also observed.

  9. An evaluation of strontium chloride, Rappaport and strontium selenite enrichment for the isolation of salmonellas from man, animals, meat products and abbattoir effluents

    PubMed Central

    Iveson, J. B.; Mackay-Scollay, E. M.

    1972-01-01

    Strontium chloride enrichment broth was found to be comparable to Rappaport broth for the recovery of a wide range of Salmonella serotypes from man, animals, meat products and effluents. With the exception of cloacal samples from reptiles, both procedures were superior to selenite F. The performance of strontium chloride Mand selenite F enrichment was improved when effluent samples were incubated at 43° C. Strontium chloride M and Rappaport enrichment were superior to selenite F for the isolation of Arizona species from reptiles. Strontium chloride B, strontium selenite and Rappaport broths were found suitable for the isolation of multiple Salmonella serotypes from sea water contaminated with abattoir effluents. The strontium chloride B and strontium selenite enrichment media were superior to Rappaport broth when samples were incubated at 43° C. Modified bismuth sulphite agar was found superior to Salmonella—Shigella agar as a solid subculture medium. The investigation of a food poisoning outbreak due to Salmonella typhimurium phage type 21 is reported. The significance of the choice of sampling and isolation techniques in salmonellosis in man and animals is discussed. PMID:4503874

  10. Influence of pH, competing ions, and salinity on the sorption of strontium and cobalt onto biogenic hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Handley-Sidhu, Stephanie; Mullan, Thomas K.; Grail, Quentin; Albadarneh, Malek; Ohnuki, Toshihiko; Macaskie, Lynne E.

    2016-03-01

    Anthropogenic radionuclides contaminate a range of environments as a result of nuclear activities, for example, leakage from waste storage tanks/ponds (e.g. Hanford, USA or Sellafield sites, UK) or as a result of large scale nuclear accidents (e.g. Chernobyl, Ukraine or Fukushima, Japan). One of the most widely applied remediation techniques for contaminated waters is the use of sorbent materials (e.g. zeolites and apatites). However, a key problem at nuclear contaminated sites is the remediation of radionuclides from complex chemical environments. In this study, biogenic hydroxyapatite (BHAP) produced by Serratia sp. bacteria was investigated for its potential to remediate surrogate radionuclides (Sr2+ and Co2+) from environmentally relevant waters by varying pH, salinity and the type and concentration of cations present. The sorption capacity of the BHAP for both Sr2+ and Co2+ was higher than for a synthetically produced hydroxyapatite (HAP) in the solutions tested. BHAP also compared favorably against a natural zeolite (as used in industrial decontamination) for Sr2+ and Co2+ uptake from saline waters. Results confirm that hydroxyapatite minerals of high surface area and amorphous calcium phosphate content, typical for biogenic sources, are suitable restoration or reactive barrier materials for the remediation of complex contaminated environments or wastewaters.

  11. Influence of pH, competing ions, and salinity on the sorption of strontium and cobalt onto biogenic hydroxyapatite

    PubMed Central

    Handley-Sidhu, Stephanie; Mullan, Thomas K.; Grail, Quentin; Albadarneh, Malek; Ohnuki, Toshihiko; Macaskie, Lynne E.

    2016-01-01

    Anthropogenic radionuclides contaminate a range of environments as a result of nuclear activities, for example, leakage from waste storage tanks/ponds (e.g. Hanford, USA or Sellafield sites, UK) or as a result of large scale nuclear accidents (e.g. Chernobyl, Ukraine or Fukushima, Japan). One of the most widely applied remediation techniques for contaminated waters is the use of sorbent materials (e.g. zeolites and apatites). However, a key problem at nuclear contaminated sites is the remediation of radionuclides from complex chemical environments. In this study, biogenic hydroxyapatite (BHAP) produced by Serratia sp. bacteria was investigated for its potential to remediate surrogate radionuclides (Sr2+ and Co2+) from environmentally relevant waters by varying pH, salinity and the type and concentration of cations present. The sorption capacity of the BHAP for both Sr2+ and Co2+ was higher than for a synthetically produced hydroxyapatite (HAP) in the solutions tested. BHAP also compared favorably against a natural zeolite (as used in industrial decontamination) for Sr2+ and Co2+ uptake from saline waters. Results confirm that hydroxyapatite minerals of high surface area and amorphous calcium phosphate content, typical for biogenic sources, are suitable restoration or reactive barrier materials for the remediation of complex contaminated environments or wastewaters. PMID:26988070

  12. Influence of pH, competing ions, and salinity on the sorption of strontium and cobalt onto biogenic hydroxyapatite.

    PubMed

    Handley-Sidhu, Stephanie; Mullan, Thomas K; Grail, Quentin; Albadarneh, Malek; Ohnuki, Toshihiko; Macaskie, Lynne E

    2016-03-18

    Anthropogenic radionuclides contaminate a range of environments as a result of nuclear activities, for example, leakage from waste storage tanks/ponds (e.g. Hanford, USA or Sellafield sites, UK) or as a result of large scale nuclear accidents (e.g. Chernobyl, Ukraine or Fukushima, Japan). One of the most widely applied remediation techniques for contaminated waters is the use of sorbent materials (e.g. zeolites and apatites). However, a key problem at nuclear contaminated sites is the remediation of radionuclides from complex chemical environments. In this study, biogenic hydroxyapatite (BHAP) produced by Serratia sp. bacteria was investigated for its potential to remediate surrogate radionuclides (Sr(2+) and Co(2+)) from environmentally relevant waters by varying pH, salinity and the type and concentration of cations present. The sorption capacity of the BHAP for both Sr(2+) and Co(2+) was higher than for a synthetically produced hydroxyapatite (HAP) in the solutions tested. BHAP also compared favorably against a natural zeolite (as used in industrial decontamination) for Sr(2+) and Co(2+) uptake from saline waters. Results confirm that hydroxyapatite minerals of high surface area and amorphous calcium phosphate content, typical for biogenic sources, are suitable restoration or reactive barrier materials for the remediation of complex contaminated environments or wastewaters.

  13. Evaluation of Cuprimine® and Syprine® for decorporation of radioisotopes of cesium, cobalt, iridium and strontium.

    PubMed

    Levitskaia, Tatiana G; Creim, Jeffrey A; Curry, Terry L; Luders, Teresa; Peterson, James M; Thrall, Karla D; Levinson, Barry

    2011-08-01

    Cuprimine® and Syprine® are therapeutics approved by the USFDA to treat copper overload in Wilson Disease (a genetic defect in copper transport) by chelation and accelerated excretion of internally-deposited copper. These oral therapeutics are based on the respective active ingredients D-penicillamine (DPA) and N,N'-bis (2-aminoethyl) -1,2-ethanediamine dihydrochloride (Trien). Cuprimine is considered the primary treatment, although physicians are increasingly turning to Syprine as a first-line therapy. Both drugs exhibit oral systemic activity and low toxicity; their biological effects and safety are established. Previous in vivo studies using a rodent animal model established the decorporation potential of Cuprimine and Syprine for (60)Co and (210)Po. Currently these studies are being expanded to evaluate the in vivo decorporation efficacy of these drugs for several additional radionuclides. In this report, results of this investigation are discussed using the radionuclides (137)Cs, (60)Co, (192)Ir and (85)Sr. Short-term 48-h pilot studies were undertaken to evaluate DPA and Trien for their in vivo decorporation potential using male Wistar-Han rats. In these studies, a radionuclide solution was administered to the animals by intravenous (IV) injection, followed by a single IV dose of either DPA or Trien. Control animals received the radionuclide alone. Results show effective decorporation of (60)Co by DPA within the time frame evaluated. DPA and Trien were also modestly effective in decorporation of (137)Cs and (85)Sr, respectively. The study did not find DPA or Trien effective for decorporation of (192)Ir. Based on these encouraging findings, further studies to evaluate the dose-response profiles and timing of the chelator administration post exposure to radionuclides are warranted.

  14. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung epithelial cells.

    PubMed

    Xie, Hong; Smith, Leah J; Holmes, Amie L; Zheng, Tongzhang; Pierce Wise, John

    2016-05-01

    Cobalt is a toxic metal used in various industrial applications leading to adverse lung effects by inhalation. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells, especially normal lung epithelial cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in normal primary human lung epithelial cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble and particulate cobalt induced similar cytotoxicity while soluble cobalt was more genotoxic than particulate cobalt. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung epithelial cells. © 2016 Wiley Periodicals, Inc.

  15. Synthesis and Staging of the Phase Formation for Strontium Ferrites in Thermal and Radiation-Thermal Reactions

    NASA Astrophysics Data System (ADS)

    Ancharova, U. V.; Mikhailenko, M. A.; Tolochko, B. P.; Lyakhov, N. Z.; Korobeinikov, M. V.; Bryazgin, A. A.; Bezuglov, V. V.; Shtarklev, E. A.; Vlasov, A. Yu; Vinokurov, Z. S.

    2015-04-01

    The strontium ferrite radiation-thermal synthesis process due to heating by intensive electron beam is described. The radiation-thermal and thermal strontium ferrite synthesis processes kinetics were studied and compared.

  16. Rapid phase synthesis of nanocrystalline cobalt ferrite

    SciTech Connect

    Shanmugavel, T.; Raj, S. Gokul; Rajarajan, G.; Kumar, G. Ramesh

    2014-04-24

    Synthesis of single phase nanocrystalline Cobalt Ferrite (CoFe{sub 2}O{sub 4}) was achieved by single step autocombustion technique with the use of citric acid as a chelating agent in mono proportion with metal. Specimens prepared with this method showed significantly higher initial permeability's than with the conventional process. Single phase nanocrystalline cobalt ferrites were formed at very low temperature. Surface morphology identification were carried out by transmission electron microscopy (TEM) analysis. The average grain size and density at low temperature increased gradually with increasing the temperature. The single phase formation is confirmed through powder X-ray diffraction analysis. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors. Temperature dependent magnetization results showed improved behavior for the nanocrystalline form of cobalt ferrite when compared to the bulk nature of materials synthesized by other methods.

  17. Controlled cobalt doping in biogenic magnetite nanoparticles

    PubMed Central

    Byrne, J. M.; Coker, V. S.; Moise, S.; Wincott, P. L.; Vaughan, D. J.; Tuna, F.; Arenholz, E.; van der Laan, G.; Pattrick, R. A. D.; Lloyd, J. R.; Telling, N. D.

    2013-01-01

    Cobalt-doped magnetite (CoxFe3 −xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites. PMID:23594814

  18. Total quality management of cobalt-60 sources

    NASA Astrophysics Data System (ADS)

    Malkoske, G. R.

    1999-06-01

    Total Quality Management of Cobalt-60 sources by a supplier requires a life cycle approach to source management. This covers various aspects, including design, manufacturing, installation, field inspection, source surveillance and return of cobalt-60 sources at the end of their useful life. The Total Quality Management approach demonstrates a strong industry commitment to the beneficial use of gamma technology for industrial irradiation applications in both developed nations and in those nations who are developing their infrastructure and techniques for the beneficial use of this technology. MDS Nordion continues to demonstrate its support and commitment to the industry by developing and implementing state-of-the-art standards for the safe use of cobalt-60 sources.

  19. Nickel cobalt phosphorous low stress electroplating

    NASA Technical Reports Server (NTRS)

    Engelhaupt, Darell E. (Inventor); Ramsey, Brian D. (Inventor)

    2002-01-01

    An electrolytic plating process is provided for electrodepositing a nickel or nickel cobalt alloy which contains at least about 2% to 25% by atomic volume of phosphorous. The process solutions contains nickel and optionally cobalt sulfate, hypophosphorous acid or a salt thereof, boric acid or a salt thereof, a monodentate organic acid or a salt thereof, and a multidentate organic acid or a salt thereof. The pH of the plating bath is from about 3.0 to about 4.5. An electroplating process is also provided which includes electroplating from the bath a nickel or nickel cobalt phosphorous alloy. This process can achieve a deposit with high microyield of at least about 84 kg/mm.sup.2 (120 ksi) and a density lower than pure nickel of about 8.0 gm/cc. This process can be used to plate a deposit of essentially zero stress at plating temperatures from ambient to 70.degree. C.

  20. Strontium migration in a crystalline medium: effects of the presence of bentonite colloids

    NASA Astrophysics Data System (ADS)

    Albarran, Nairoby; Missana, Tiziana; García-Gutiérrez, Miguel; Alonso, Ursula; Mingarro, Manuel

    2011-03-01

    The effects of bentonite colloids on strontium migration in fractured crystalline medium were investigated. We analyzed first the transport behaviour of bentonite colloids alone at different flow rates; then we compared the transport behaviour of strontium as solute and of strontium previously adsorbed onto stable bentonite colloids at a water velocity of approximately 7.1·10 - 6 m/s-224 m/yr. Experiments with bentonite colloids alone showed that - at the lowest water flow rate used in our experiments (7.1·10 - 6 m/s) - approximately 70% of the initially injected colloids were retained in the fracture. Nevertheless, the mobile colloidal fraction, moved through the fracture without retardation, at any flow rate. Bentonite colloids deposited over the fracture surface were identified during post-mortem analyses. The breakthrough curve of strontium as a solute, presented a retardation factor, Rf ~ 6, in agreement with its sorption onto the granite fracture surface. The breakthrough curve of strontium in the presence of bentonite colloids was much more complex, suggesting additional contributions of colloids to strontium transport. A very small fraction of strontium adsorbed on mobile colloids moved un-retarded ( Rf = 1) and this fraction was much lower than the expected, considering the quantity of strontium initially adsorbed onto colloids (90%). This behaviour suggests the hypothesis of strontium sorption reversibility from colloids. On the other hand, bentonite colloids retained within the granite fracture played a major role, contributing to a slower strontium transport in comparison with strontium as a solute. This was shown by a clear peak in the breakthrough curve corresponding to a retardation factor of approximately 20.

  1. Monitoring bone strontium levels of an osteoporotic subject due to self-administration of strontium citrate with a novel diagnostic tool, in vivo XRF: a case study.

    PubMed

    Moise, H; Adachi, J D; Chettle, D R; Pejović-Milić, A

    2012-07-01

    A previously developed in vivo X-ray fluorescence (IVXRF) I-125 based system was used to measure bone strontium levels non-invasively in an osteoporotic female volunteer. The volunteer was recruited in December 2008, as part of the Ryerson and McMaster University Strontium in Bone Research Study and measured at twice weekly, weekly and monthly intervals. Thirty minute measurements were taken at the finger and ankle bone sites, representing primarily cortical and trabecular bone, respectively and the strontium K-alpha X-ray peak at 14.16 keV was used in the analysis. Since the volunteer had no prior history of strontium based medications or supplementation, baseline natural strontium levels were obtained followed by a 24h measurement of first intake of strontium citrate supplements (680 mg Sr/day). While the baseline levels of 0.38 ± 0.05 and 0.39 ± 0.10 for the finger and ankle, respectively, were on par with those previously reported in Caucasians among twenty-two healthy non-supplementing strontium individuals by our group, an increase began to be seen after 24 hrs of 0.62 ± 0.14 and 0.45 ± 0.12 for the finger and ankle, respectively. By 120 h, the increase was statistically significant at 0.68 ± 0.07 and 0.93 ± 0.05, respectively. Further increases occurred within an interval of 90-180 days, with the most recent, after 800 days, at the finger and ankle being 7 and 15 times higher than the initial baseline reading. The intriguing results show bone strontium incorporation and retention follow a pattern, suggesting strontium levels, at least in the ankle, do not plateau within two to three years and will continue to increase over time, as an individual takes strontium supplements. The ability of this IVXRF system to monitor and measure bone strontium levels over time provides a useful diagnostic tool to help gain insight into strontium bone kinetics.

  2. Growth and micro structural studies on Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) buffer layers

    SciTech Connect

    Srinivas, S.; Bhatnagar, A.K.; Pinto, R.

    1994-12-31

    Microstructure of Yittria Stabilized Zirconia (YSZ) and Strontium Titanate (STO) of radio frequency magnetron sputtered buffer layers was studied at various sputtering conditions on Si<100>, Sapphire and LaAlO{sub 3} <100> substrates. The effect of substrate temperatures upto 800 C and sputtering gas pressures in the range of 50 mTorr. of growth conditions was studied. The buffer layers of YSZ and STO showed a strong tendency for columnar structure with variation growth conditions. The buffer layers of YSZ and STO showed orientation. The tendency for columnar growth was observed above 15 mTorr sputtering gas pressure and at high substrate temperatures. Post annealing of these films in oxygen atmosphere reduced the oxygen deficiency and strain generated during growth of the films. Strong c-axis oriented superconducting YBa{sub 2}Cu{sub 9}O{sub 7-x} (YBCO) thin films were obtained on these buffer layers using pulsed laser ablation technique. YBCO films deposited on multilayers of YSZ and STO were shown to have better superconducting properties.

  3. Genome-wide analysis of caesium and strontium accumulation in Saccharomyces cerevisiae.

    PubMed

    Heuck, Sabine; Gerstmann, Udo C; Michalke, Bernhard; Kanter, Ulrike

    2010-10-01

    (137)Cs and (90)Sr contribute to significant and long-lasting contamination of the environment with radionuclides. Due to their relatively high biological availability, they are transferred rapidly into biotic systems and may enter the food chain. In this study, we analysed 4862 haploid yeast knockout strains of Saccharomyces cerevisiae to identify genes involved in caesium (Cs(+)) and/or strontium (Sr(2+)) accumulation. According to this analysis, 212 mutant strains were associated with reproducible altered Cs(+) and/or Sr(2+) accumulation. These mutants were deficient for a wide range of cellular processes. Among those, the vacuolar function and biogenesis turned out to be crucial for both Cs(+) and Sr(2+) accumulation. Disruption of the vacuole diminished Cs(+) accumulation, whereas Sr(2+) enrichment was enhanced. Further analysis with a subset of the identified candidates were undertaken comparing the accumulation of Cs(+) and Sr(2+) with their essential counterparts potassium (K(+)) and calcium (Ca(2+)). Sr(2+) and Ca(2+) accumulation was highly correlated in yeast excluding the possibility of a differential regulation or uptake mechanisms. In direct contrast, the respective results suggest that Cs(+) uptake is at least partially dependent on mechanisms distinct from K(+) uptake. Single candidates (e.g. KHA1) are presented which might be specifically responsible for Cs(+) homeostasis.

  4. Corrosion behavior and biocompatibility of strontium and fluorine co-doped electrodeposited hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Ding, Qiongqiong; Pang, Xiaofeng; Han, Shuguang; Yan, Yajing

    2013-10-01

    To improve the corrosion resistance and biocompatibility of biomedical titanium, strontium (Sr) and fluorine (F) were simultaneously incorporated in hydroxyapatite (HAp) to form SrFHAp coating on titanium (Ti) via electrodeposition. The microstructure, phase composition, corrosion resistance, and cytocompatibility of the films were studied. Results revealed that by incorporating F- and Sr2+ ions in HAp, the density of the coating markedly increased, i.e., a lower porosity than common HAp coating. The SrFHAp layer was dense and uniform, with nano-needle-like crystals of apatite, which aligned vertically to the substrate. The SrFHAp crystals were calcium-deficient apatite, and Sr2+ ions and F- ions were homogeneously distributed in the coating. The SrFHAp coating showed lower dissolution rate than HA coating. Potentiodynamic polarization test manifested that the SrFHAp-coated titanium exhibited superior corrosion resistance than HAp single-coated sample. In addition, osteoblasts cellular tests revealed that the SrFHAp coating was more effective to improve the in vitro biocompatibility of Ti compared with HAp coating.

  5. Thyroid hormones and metabolic rate during induction of Vitamin B12 deficiency in goats.

    PubMed

    Mburu, J N; Kamau, J M; Badamana, M S

    1994-10-01

    Vitamin B12 deficiency was induced in 15 small East African goats by feeding cobalt deficient Chloris gayana hay (containing 0.02 mg of Co/kg dry matter) over a 25 week experimental period. Cobalt was supplemented as an oral drench to supply 0.3 g of Co/goat/week to 15 treated goats. At intervals of 3-4 weeks, serum concentrations of Vitamin B12 , total thyroxine (TT4), free tetra-iodothyronine (FT4) and free tri-iodothyronine (FT3) were determined by radioimmunoassay, while the rate of resting metabolism was determined by measuring the goats' rate of oxygen consumption. Serum Vitamin B12 concentration was significantly higher (p<0.01) in cobalt-treated (289.6 +/- 40.76 pg/ml) than in control (142.8 +/- 28.27 pg/ml) goats. The mean serum TT4 concentration was significantly (p<0.01) higher in control (59.0 +/- 1.70 nmol/l) than in cobalt-treated (51.6 +/- 2.45 nmol/l) goats. However, the levels of FT4, FT3 and the rate of resting metabolism were unaffected by the goats' cobalt status. Furthermore, the goats did not lose weight or become anaemic.

  6. Cobalt-based Catalysts for Ammonia Decomposition

    PubMed Central

    Lendzion-Bielun, Zofia; Narkiewicz, Urszula; Arabczyk, Walerian

    2013-01-01

    An effect of promoters such as calcium, aluminium, and potassium oxides and also addition of chromium and manganese on the structure of cobalt catalysts was examined. Studies of the catalytic ammonia decomposition over the cobalt catalysts are presented. The studies of the ammonia decomposition were carried out for various ammonia-hydrogen mixtures in which ammonia concentration varied in the range from 10% to 100%. Co(0) catalyst, promoted by oxides of aluminium, calcium, and potassium, showed the highest activity in the ammonia decomposition reaction. Contrary to expectations, it was found that chromium and manganese addition into the catalysts decreased their activity. PMID:28809280

  7. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  8. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  9. International strategic minerals inventory summary report; cobalt

    USGS Publications Warehouse

    Crockett, R.N.; Chapman, G.R.; Forrest, M.D.

    1987-01-01

    Major world resources of cobalt are described in this summary report of information in the International Strategic Minerals Inventory {ISMI}. ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of cobalt on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

  10. 40 CFR 721.10202 - Benzoic acid, 4-chloro-2- [(substituted)azo]-, strontium salt (1:1) (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzoic acid, 4-chloro-2- -, strontium... New Uses for Specific Chemical Substances § 721.10202 Benzoic acid, 4-chloro-2- -, strontium salt (1:1... identified generically as benzoic acid, 4-chloro-2- -, strontium salt (1:1) (PMN P-08-701) is subject to...

  11. 40 CFR 721.10202 - Benzoic acid, 4-chloro-2- [(substituted)azo]-, strontium salt (1:1) (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzoic acid, 4-chloro-2- -, strontium... New Uses for Specific Chemical Substances § 721.10202 Benzoic acid, 4-chloro-2- -, strontium salt (1:1... identified generically as benzoic acid, 4-chloro-2- -, strontium salt (1:1) (PMN P-08-701) is subject to...

  12. 40 CFR 721.10202 - Benzoic acid, 4-chloro-2- [(substituted)azo]-, strontium salt (1:1) (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzoic acid, 4-chloro-2- -, strontium... New Uses for Specific Chemical Substances § 721.10202 Benzoic acid, 4-chloro-2- -, strontium salt (1:1... identified generically as benzoic acid, 4-chloro-2- -, strontium salt (1:1) (PMN P-08-701) is subject to...

  13. 40 CFR 721.10202 - Benzoic acid, 4-chloro-2- [(substituted)azo]-, strontium salt (1:1) (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzoic acid, 4-chloro-2- -, strontium... New Uses for Specific Chemical Substances § 721.10202 Benzoic acid, 4-chloro-2- -, strontium salt (1:1... identified generically as benzoic acid, 4-chloro-2- -, strontium salt (1:1) (PMN P-08-701) is subject to...

  14. 10 CFR 32.61 - Ice detection devices containing strontium-90; requirements for license to manufacture or...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Ice detection devices containing strontium-90... Generally Licensed Items § 32.61 Ice detection devices containing strontium-90; requirements for license to... ice detection devices containing strontium-90 for distribution to persons generally licensed under...

  15. 10 CFR 32.61 - Ice detection devices containing strontium-90; requirements for license to manufacture or...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Ice detection devices containing strontium-90... Generally Licensed Items § 32.61 Ice detection devices containing strontium-90; requirements for license to... ice detection devices containing strontium-90 for distribution to persons generally licensed under...

  16. 10 CFR 32.61 - Ice detection devices containing strontium-90; requirements for license to manufacture or...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Ice detection devices containing strontium-90... Generally Licensed Items § 32.61 Ice detection devices containing strontium-90; requirements for license to... ice detection devices containing strontium-90 for distribution to persons generally licensed under...

  17. 10 CFR 32.61 - Ice detection devices containing strontium-90; requirements for license to manufacture or...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Ice detection devices containing strontium-90... Generally Licensed Items § 32.61 Ice detection devices containing strontium-90; requirements for license to... ice detection devices containing strontium-90 for distribution to persons generally licensed under...

  18. 10 CFR 32.61 - Ice detection devices containing strontium-90; requirements for license to manufacture or...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Ice detection devices containing strontium-90... Generally Licensed Items § 32.61 Ice detection devices containing strontium-90; requirements for license to... ice detection devices containing strontium-90 for distribution to persons generally licensed under...

  19. 40 CFR 721.5253 - 2-Naphthalenecarboxylic acid, 4,4′-methylenebis [3-hydroxy-, strontium salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-methylenebis [3-hydroxy-, strontium salt. 721.5253 Section 721.5253 Protection of Environment ENVIRONMENTAL...′-methylenebis [3-hydroxy-, strontium salt. (a) Chemical substance and significant new uses subject to reporting...-, strontium salt (PMN P-99-1341; CAS No. 235083-90-6) is subject to reporting under this section for...

  20. 40 CFR 721.5253 - 2-Naphthalenecarboxylic acid, 4,4′-methylenebis [3-hydroxy-, strontium salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-methylenebis [3-hydroxy-, strontium salt. 721.5253 Section 721.5253 Protection of Environment ENVIRONMENTAL...′-methylenebis [3-hydroxy-, strontium salt. (a) Chemical substance and significant new uses subject to reporting...-, strontium salt (PMN P-99-1341; CAS No. 235083-90-6) is subject to reporting under this section for...

  1. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells.

    PubMed

    Smith, Leah J; Holmes, Amie L; Kandpal, Sanjeev Kumar; Mason, Michael D; Zheng, Tongzhang; Wise, John Pierce

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity.

  2. Preparation of cobalt nanoparticles by hydrogen reduction of cobalt chloride in the gas phase

    SciTech Connect

    Jang, Hee Dong; Hwang, Dae Won; Kim, Dong Pyo; Kim, Heon Chang; Lee, Byung Yoon; Jeong, In Bum

    2004-01-03

    Cobalt nanoparticles were produced by the hydrogen reduction of cobalt chloride vapor in a multistage tubular aerosol flow reactor. Reaction zone temperature, preheating temperature, mole fractions of CoCl{sub 2} and H{sub 2}, and residence time were considered as key process variables for the control of particle size and size distribution. Ranging from 50 to 78 nm in average diameter, cobalt nanoparticles with narrow size distributions were synthesized throughout our experiments. All of the considered process variables affected the particle size and size distribution in the synthesis of cobalt nanoparticles. As the reaction zone temperature and the CoCl{sub 2} mole fraction increased, the average particle diameter increased. But the average particle diameter decreased as the residence time of reactants increased.

  3. Toxicity and bioactivity of cobalt nanoparticles on the monocytes.

    PubMed

    Liu, Ya-ke; Ye, Jun; Han, Qing-lin; Tao, Ran; Liu, Fan; Wang, Wei

    2015-05-01

    To explore the toxicity and biological activity of cobalt nanoparticles on the osteoclasts. Analyze the relationship between cobalt nanoparticles and osteolysis. Monocyte-macrophages (RAW 264.7) was cultured in vitro, osteoclast-like cells were induced by lipopolysaccharides (LPS). After RAW 264.7 was induced for 24 h, Methyl Thiazolium Tetrazolium (MTT) biological toxicity test of osteoclast-like cell was preceded using Cobalt nanoparticles (set 4 concentrations: 10, 20, 50, 100 μM) and cobalt chloride (set 4 concentrations: 10, 20, 50, 100 μM) at 2, 4, 8, 24 and 48 h respectively. The relative expression of mRNA of CA II and Cat K after RAW 264.7 induction was determined by Q-PCR. mRNA relative expression of CA II, Cat K were reduced at multiple concentrations both cobalt nanoparticles and cobalt chloride, and was time and concentration dependent, cobalt nanoparticles are more significant than cobalt chloride group. But when the cobalt nanoparticles concentration is in 10-50 μM, the mRNA relative expression of CA II, Cat K increased. Cobalt nanoparticles have biological toxicity. At multiple concentrations, the differentiation and proliferation of osteoclasts was inhibited, but when the concentration of cobalt nanoparticles is in 10-50 μM, it has been strengthened. © 2015 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.

  4. Determination of variables in the prediction of strontium distribution coefficients for selected sediments

    USGS Publications Warehouse

    Pace, M.N.; Rosentreter, J.J.; Bartholomay, R.C.

    2001-01-01

    Idaho State University and the US Geological Survey, in cooperation with the US Department of Energy, conducted a study to determine and evaluate strontium distribution coefficients (Kds) of subsurface materials at the Idaho National Engineering and Environmental Laboratory (INEEL). The Kds were determined to aid in assessing the variability of strontium Kds and their effects on chemical transport of strontium-90 in the Snake River Plain aquifer system. Data from batch experiments done to determine strontium Kds of five sediment-infill samples and six standard reference material samples were analyzed by using multiple linear regression analysis and the stepwise variable-selection method in the statistical program, Statistical Product and Service Solutions, to derive an equation of variables that can be used to predict strontium Kds of sediment-infill samples. The sediment-infill samples were from basalt vesicles and fractures from a selected core at the INEEL; strontium Kds ranged from ???201 to 356 ml g-1. The standard material samples consisted of clay minerals and calcite. The statistical analyses of the batch-experiment results showed that the amount of strontium in the initial solution, the amount of manganese oxide in the sample material, and the amount of potassium in the initial solution are the most important variables in predicting strontium Kds of sediment-infill samples.

  5. Strontium Isotope Signals in Cremated Petrous Portions as Indicator for Childhood Origin

    PubMed Central

    Harvig, Lise; Frei, Karin Margarita; Price, T. Douglas; Lynnerup, Niels

    2014-01-01

    Dental enamel is currently of high informative value in studies concerning childhood origin and human mobility because the strontium isotope ratio in human dental enamel is indicative of geographical origin. However, many prehistoric burials involve cremation and although strontium retains its original biological isotopic composition, even when exposed to very high temperatures, intact dental enamel is rarely preserved in cremated or burned human remains. When preserved, fragments of dental enamel may be difficult to recognize and identify. Finding a substitute material for strontium isotope analysis of burned human remains, reflecting childhood values, is hence of high priority. This is the first study comparing strontium isotope ratios from cremated and non-cremated petrous portions with enamel as indicator for childhood origin. We show how strontium isotope ratios in the otic capsule of the petrous portion of the inner ear are highly correlated with strontium isotope ratios in dental enamel from the same individual, whether inhumed or cremated. This implies that strontium isotope ratios in the petrous bone, which practically always survives cremation, are indicative of childhood origin for human skeletal remains. Hence, the petrous bone is ideal as a substitute material for strontium isotope analysis of burned human remains. PMID:25010496

  6. Full-Scale and Bench-Scale Studies on the Removal of Strontium from Water (abstract)

    EPA Science Inventory

    Strontium (Sr) is a natural and commonly occurring alkaline earth metal which has an oxidation state of +2 under normal environmental conditions. Stable strontium is suspended in water and is dissolved after water runs through rocks and soil. It behaves very similar to calcium. G...

  7. Repumping of ultracold strontium atoms using the ^3P2 - ^3D2 transition

    NASA Astrophysics Data System (ADS)

    Mickelson, P. G.; Martinez de Escobar, Y. N.; Traverso, A. J.; Killian, T. C.

    2008-05-01

    We discuss recent experiments involving ultracold strontium. Using a commercially-available 3 micron laser, we repump atoms out of the ^3P2 level via the ^3D2 state and gain almost a factor of 10 in the number of atoms in our system. This increase in the signal-to-noise ratio enables improved spectroscopy of strontium in our optical trap.

  8. Intestinal absorption of strontium chloride in healthy volunteers: pharmacokinetics and reproducibility

    PubMed Central

    SIPS, A. J. A. M.; van der VIJGH, W. J. F.; BARTO, R.; NETELENBOS, J. C.

    1996-01-01

    1The absorption kinetics of orally administered strontium chloride and its reproducibility were investigated in healthy volunteers after administering strontium either under fasting conditions (study I, n=8) or in combination with a standardized meal (study II, n=8). Each subject received strontium orally at day 0, 14, and 28 and intravenously at day 42. The study was performed as part of a project in which a simple clinical test for measuring intestinal calcium absorption is being developed, based on the use of stable strontium as a marker. 2Plasma strontium concentration–time curves were analysed by noncompartment analysis and a four compartment disposition model. Within a volunteer each oral curve was fitted simultaneously with the intravenous curve, by which means a two segment model for absorption was revealed. 3Mean absolute bioavailability of strontium was 25% without a meal and 19% with a meal, whereas the intraindividual variation was 24% and 20%, respectively. 4Various limited sampling absorption parameters were determined in order to select a potential test parameter for measuring intestinal calcium absorption using strontium as a marker. Fractional absorption at 4 h (Fc240), obtained after co-ingestion of strontium with a meal, appeared to be the best test parameter, because it represented bioavailability well (r=0.90). PMID:8799520

  9. Strontium localization in bone tissue studied by X-ray absorption spectroscopy.

    PubMed

    Frankær, Christian Grundahl; Raffalt, Anders Christer; Stahl, Kenny

    2014-02-01

    Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X-ray absorption spectra resulted in a compositional model and allowed the relative distribution of strontium in the different bone components to be estimated. Approximately 35-45% of the strontium present is incorporated into calcium hydroxyapatite (CaHA) by substitution of some of the calcium ions occupying highly ordered sites, and at least 30% is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is surrounded by only oxygen atoms similar to Sr(2+) in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher structural order than when present in serum but less order than when it is incorporated into CaHA. The total amount of strontium in the samples was determined by inductively coupled plasma mass spectrometry, and the amount of Sr was found to increase with increasing dose levels and treatment periods, whereas the relative distribution of strontium among the different components appears to be independent of treatment period and dose level.

  10. Full-Scale and Bench-Scale Studies on the Removal of Strontium from Water (abstract)

    EPA Science Inventory

    Strontium (Sr) is a natural and commonly occurring alkaline earth metal which has an oxidation state of +2 under normal environmental conditions. Stable strontium is suspended in water and is dissolved after water runs through rocks and soil. It behaves very similar to calcium. G...

  11. Strontium eluting graphene hybrid nanoparticles augment osteogenesis in a 3D tissue scaffold.

    PubMed

    Kumar, Sachin; Chatterjee, Kaushik

    2015-02-07

    The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium particles. Thermal gravimetric analysis further confirmed the composition of the hybrid particles as 22 wt% of strontium. Macroporous tissue scaffolds were prepared by incorporating RGO_Sr particles in poly(ε-caprolactone) (PCL). The PCL/RGO_Sr scaffolds were found to elute strontium ions in aqueous medium. Osteoblast proliferation and differentiation was significantly higher in the PCL scaffolds containing the RGO_Sr particles in contrast to neat PCL and PCL/RGO scaffolds. The increased biological activity can be attributed to the release of strontium ions from the hybrid nanoparticles. This study demonstrates that composites prepared using hybrid nanoparticles that elute strontium ions can be used to prepare multifunctional scaffolds with good mechanical and osteoinductive properties. These findings have important implications for designing the next generation of biomaterials for use in tissue regeneration.

  12. Strontium isotope signals in cremated petrous portions as indicator for childhood origin.

    PubMed

    Harvig, Lise; Frei, Karin Margarita; Price, T Douglas; Lynnerup, Niels

    2014-01-01

    Dental enamel is currently of high informative value in studies concerning childhood origin and human mobility because the strontium isotope ratio in human dental enamel is indicative of geographical origin. However, many prehistoric burials involve cremation and although strontium retains its original biological isotopic composition, even when exposed to very high temperatures, intact dental enamel is rarely preserved in cremated or burned human remains. When preserved, fragments of dental enamel may be difficult to recognize and identify. Finding a substitute material for strontium isotope analysis of burned human remains, reflecting childhood values, is hence of high priority. This is the first study comparing strontium isotope ratios from cremated and non-cremated petrous portions with enamel as indicator for childhood origin. We show how strontium isotope ratios in the otic capsule of the petrous portion of the inner ear are highly correlated with strontium isotope ratios in dental enamel from the same individual, whether inhumed or cremated. This implies that strontium isotope ratios in the petrous bone, which practically always survives cremation, are indicative of childhood origin for human skeletal remains. Hence, the petrous bone is ideal as a substitute material for strontium isotope analysis of burned human remains.

  13. 10 CFR 35.2433 - Records of decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of decay of strontium-90 sources for ophthalmic... Records § 35.2433 Records of decay of strontium-90 sources for ophthalmic treatments. (a) A licensee shall....432; and (2) For each decay calculation, the date and the source activity as determined under § 35.433. ...

  14. 10 CFR 35.433 - Decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Decay of strontium-90 sources for ophthalmic treatments... Brachytherapy § 35.433 Decay of strontium-90 sources for ophthalmic treatments. (a) Only an authorized medical... times for ophthalmic treatments. The decay must be based on the activity determined under § 35.432. (b...

  15. 10 CFR 35.433 - Decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Decay of strontium-90 sources for ophthalmic treatments... Brachytherapy § 35.433 Decay of strontium-90 sources for ophthalmic treatments. (a) Only an authorized medical... times for ophthalmic treatments. The decay must be based on the activity determined under § 35.432. (b...

  16. 10 CFR 35.2433 - Records of decay of strontium-90 sources for ophthalmic treatments.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Records of decay of strontium-90 sources for ophthalmic... Records § 35.2433 Records of decay of strontium-90 sources for ophthalmic treatments. (a) A licensee shall....432; and (2) For each decay calculation, the date and the source activity as determined under § 35.433. ...

  17. The use of synthesized aqueous solutions for determining strontium sorption isotherms

    USGS Publications Warehouse

    Liszewski, M.J.; Bunde, R.L.; Hemming, C.; Rosentreter, J.; Welhan, J.

    1998-01-01

    The use of synthesized aqueous solutions for determining experimentally derived strontium sorption isotherms of sediment was investigated as part of a study accessing strontium chemical transport properties. Batch experimental techniques were used to determine strontium sorption isotherms using synthesized aqueous solutions designed to chemically represent water from a natural aquifer with respect to major ionic character and pH. A strontium sorption isotherm for a sediment derived using a synthesized aqueous solution was found to be most comparable to an isotherm derived using natural water when the synthesized aqueous solution contained similar concentrations of calcium and magnesium. However, it is difficult to match compositions exactly due to the effects of disequilibrium between the solution and the sediment. Strong linear relations between sorbed strontium and solution concentrations of calcium and magnesium confirm that these cations are important co-constituents in these synthesized aqueous solutions. Conversely, weak linear relations between sorbed strontium and solution concentrations of sodium and potassium indicate that these constituents do not affect sorption of strontium. The addition of silica to the synthesized aqueous solution does not appreciably affect the resulting strontium sorption isotherm.

  18. Role of hypoxia-inducible factor 1{alpha} in modulating cobalt-induced lung inflammation.

    PubMed

    Saini, Yogesh; Kim, Kyung Y; Lewandowski, Ryan; Bramble, Lori A; Harkema, Jack R; Lapres, John J

    2010-02-01

    Hypoxia plays an important role in development, cellular homeostasis, and pathological conditions, such as cancer and stroke. There is also growing evidence that hypoxia is an important modulator of the inflammatory process. Hypoxia-inducible factors (HIFs) are a family of proteins that regulate the cellular response to oxygen deficit, and loss of HIFs impairs inflammatory cell function. There is little known, however, about the role of epithelial-derived HIF signaling in modulating inflammation. Cobalt is capable of eliciting an allergic response and promoting HIF signaling. To characterize the inflammatory function of epithelial-derived HIF in response to inhaled cobalt, a conditional lung-specific HIF1alpha, the most ubiquitously expressed HIF, deletion mouse, was created. Control mice showed classic signs of metal-induced injury following cobalt exposure, including fibrosis and neutrophil infiltration. In contrast, HIF1alpha-deficient mice displayed a Th2 response that resembled asthma, including increased eosinophilic infiltration, mucus cell metaplasia, and chitinase-like protein expression. The results suggest that epithelial-derived HIF signaling has a critical role in establishing a tissue's inflammatory response, and compromised HIF1alpha signaling biases the tissue towards a Th2-mediated reaction.

  19. Role of hypoxia-inducible factor 1α in modulating cobalt-induced lung inflammation

    PubMed Central

    Saini, Yogesh; Kim, Kyung Y.; Lewandowski, Ryan; Bramble, Lori A.; Harkema, Jack R.

    2010-01-01

    Hypoxia plays an important role in development, cellular homeostasis, and pathological conditions, such as cancer and stroke. There is also growing evidence that hypoxia is an important modulator of the inflammatory process. Hypoxia-inducible factors (HIFs) are a family of proteins that regulate the cellular response to oxygen deficit, and loss of HIFs impairs inflammatory cell function. There is little known, however, about the role of epithelial-derived HIF signaling in modulating inflammation. Cobalt is capable of eliciting an allergic response and promoting HIF signaling. To characterize the inflammatory function of epithelial-derived HIF in response to inhaled cobalt, a conditional lung-specific HIF1α, the most ubiquitously expressed HIF, deletion mouse, was created. Control mice showed classic signs of metal-induced injury following cobalt exposure, including fibrosis and neutrophil infiltration. In contrast, HIF1α-deficient mice displayed a Th2 response that resembled asthma, including increased eosinophilic infiltration, mucus cell metaplasia, and chitinase-like protein expression. The results suggest that epithelial-derived HIF signaling has a critical role in establishing a tissue's inflammatory response, and compromised HIF1α signaling biases the tissue towards a Th2-mediated reaction. PMID:19915160

  20. Elevated granulocyte strontium in inflammatory arthritides is related to the inflammatory activity

    SciTech Connect

    Haellgren, R.; Svensson, K.; Johansson, E.; Lindh, U.

    1984-12-01

    Total cellular strontium and calcium were measured by the nuclear microprobe technique. Increased mass fraction of both elements was found in granulocytes isolated from patients with active rheumatoid arthritis and other kinds of inflammatory arthritides. Increased granulocyte calcium but only marginally elevated granulocyte strontium was demonstrated in patients with scleroderma. The granulocyte accumulation of strontium and calcium seems to be linked to the degree of inflammatory activity, because the granulocyte content of both elements was positively correlated to the plasma concentration of acute-phase proteins. Corticosteroid therapy induced a marked reduction of granulocyte strontium but a more modest decrease of granulocyte calcium. The serum levels of strontium and calcium were within the normal ranges in all patients and were not significantly altered by corticosteroids. 21 references, 4 figures, 3 tables.

  1. Quantitative bioanalysis of strontium in human serum by inductively coupled plasma-mass spectrometry

    PubMed Central

    Somarouthu, Srikanth; Ohh, Jayoung; Shaked, Jonathan; Cunico, Robert L; Yakatan, Gerald; Corritori, Suzana; Tami, Joe; Foehr, Erik D

    2015-01-01

    Aim: A bioanalytical method using inductively-coupled plasma-mass spectrometry to measure endogenous levels of strontium in human serum was developed and validated. Results & methodology: This article details the experimental procedures used for the method development and validation thus demonstrating the application of the inductively-coupled plasma-mass spectrometry method for quantification of strontium in human serum samples. The assay was validated for specificity, linearity, accuracy, precision, recovery and stability. Significant endogenous levels of strontium are present in human serum samples ranging from 19 to 96 ng/ml with a mean of 34.6 ± 15.2 ng/ml (SD). Discussion & conclusion: Calibration procedures and sample pretreatment were simplified for high throughput analysis. The validation demonstrates that the method was sensitive, selective for quantification of strontium (88Sr) and is suitable for routine clinical testing of strontium in human serum samples. PMID:28031925

  2. Effects of strontium-induced stress on marine microalgae Platymonas subcordiformis (Chlorophyta: Volvocales)

    NASA Astrophysics Data System (ADS)

    Li, Mei; Xie, Xitao; Xue, Renhao; Liu, Zhili

    2006-06-01

    Strontium-induced stress in growth and chlorophyll contents of Platymonas subcordiformis was investigated under laboratory condition. The results showed that strontium exposure had little influences in general on growth and chlorophyll contents of the algae except for very high Sr concentrations. The maximum biosorption capacity of strontium ranged from 69.62 to 269.18 mg Sr2+/g dry weight. The algal biomass exhibited high uptake capacity of strontium. Total superoxide dismutase (SOD) activity and the content of lipid peroxidation products malondialdehyde (MDA) were significantly different in different treatments. SOD activity reached the highest level at 0.09 mmol/L that was about 55.8% higher than that in the control. The MDA content increased significantly at 0.36 mmol/L, which was 2.15 times higher than that in the control, indicating a state of oxidative stress. With the increase of strontium concentration, the amount of fatty acids decreased.

  3. EXAFS investigations of strontium complexation by a polymer-supported crown ether.

    SciTech Connect

    Dietz, M. L.; Jensen, M. P.; Chemistry

    2004-01-09

    Extended X-ray absorption fine-structure (EXAFS) measurements have been used to probe the coordination environment of strontium ion sorbed from aqueous nitric acid solutions on an extraction chromatographic resin comprising a macrocyclic polyether dispersed on a polymeric support. The strontium EXAFS of the metal ions sorbed onto the resin are consistent with a 1:1:2 strontium:crown ether:nitrate stoichiometry in which the strontium is enveloped in the crown ether ring and both nitrate anions are coordinated to the strontium as bidentate ligands. This is the same structure and stoichiometry observed for complexes in liquid-liquid extraction when the macrocyclic polyether is dissolved in a diluent with low water miscibility like 1-octanol.

  4. Localized comedo formation after cobalt irradiation

    SciTech Connect

    Myskowski, P.L.; Safai, B.

    1981-10-01

    Following Cobalt-60 irradiation for a left frontotemporal tumor, a 61-year-old woman developed comedones on the forehead. These changes responded to conventional acne therapy with retinoic acid. Multiple acneigenic factors were implicated in the pathogenesis of her lesions.

  5. Sintered diamond compacts using metallic cobalt binders

    NASA Technical Reports Server (NTRS)

    Libby, W. F.; Katzman, H.

    1972-01-01

    Method is developed for sintering diamond powder which uses metallic cobalt as binder. Present samples show maximum microhardness of over 3000 kg/sq mm on Knoop scale. Material may be used as hard surface coating or may compete with cubic boron nitride as abrasive grain.

  6. Evidence of Formation of Superdense Nonmagnetic Cobalt

    PubMed Central

    Banu, Nasrin; Singh, Surendra; Satpati, B.; Roy, A.; Basu, S.; Chakraborty, P.; Movva, Hema C. P.; Lauter, V.; Dev, B. N.

    2017-01-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure. PMID:28157186

  7. Hardfacing with cobalt and nickel alloys

    SciTech Connect

    Wu, J.B.C. ); Redman, J. , Los Angles, CA )

    1994-09-01

    The use of cobalt or nickel alloys for added wear resistance was initiated in the early 1900s with the development of the cobalt-chromium-tungsten family of alloys. The cobalt alloys were called the Stellite'' because of their bright, shiny, nontarnished appearance. Further development and characterization of this alloy system established its usage in unlubricated metal-to-metal contact or erosion by high-velocity fluid or solid particulate impingement. Initially, the alloys were used as solid castings but later were applied by welding to tougher or more ductile substrates, hence the birth of the hardfacing industry. Many of the original Stellite compositions are still in use, but many others, including the nickel and iron alloys, have been developed for special applications or for use by newer application procedures. Examining the microstructural features and wear properties of these families of hardfacing alloys can help in choosing the right alloy for the job. Various cobalt and nickel alloys, their available product forms and the corresponding hardfacing methods, are reviewed in this article.

  8. Solvothermal synthesis of cobalt oxides nanocrystals

    NASA Astrophysics Data System (ADS)

    Shao, Wenyao; Yan, Mengwen

    2017-05-01

    CoO and Co3O4 nanocrystals (NCs) were synthesized by a one-pot solvothermal reaction in the presence of the oxidant NaOH and the surfactant cetyltrimethyl ammonium bromide (CTAB). The as-prepared cobalt oxide nanoparticles are size uniformed and have good dispersibility and good crystallinity.

  9. Magnetization dynamics of cobalt grown on graphene

    SciTech Connect

    Berger, A. J.; White, S. P.; Adur, R.; Pu, Y.; Hammel, P. C.; Amamou, W.; Kawakami, R. K.

    2014-05-07

    Ferromagnetic resonance (FMR) spin pumping is a rapidly growing field which has demonstrated promising results in a variety of material systems. This technique utilizes the resonant precession of magnetization in a ferromagnet to inject spin into an adjacent non-magnetic material. Spin pumping into graphene is attractive on account of its exceptional spin transport properties. This article reports on FMR characterization of cobalt grown on chemical vapor deposition graphene and examines the validity of linewidth broadening as an indicator of spin pumping. In comparison to cobalt samples without graphene, direct contact cobalt-on-graphene exhibits increased FMR linewidth—an often used signature of spin pumping. Similar results are obtained in Co/MgO/graphene structures, where a 1 nm MgO layer acts as a tunnel barrier. However, magnetometry, magnetic force microscopy, and Kerr microscopy measurements demonstrate increased magnetic disorder in cobalt grown on graphene, perhaps due to changes in the growth process and an increase in defects. This magnetic disorder may account for the observed linewidth enhancement due to effects such as two-magnon scattering or mosaicity. As such, it is not possible to conclude successful spin injection into graphene from FMR linewidth measurements alone.

  10. Sol-gel entrapped cobalt complex

    SciTech Connect

    Lima, Omar J. de; Papacidero, Andrea T.; Rocha, Lucas A.; Sacco, Herica C.; Nassar, Eduardo J.; Ciuffi, Katia J.; Bueno, Luciano A.; Messaddeq, Younes; Ribeiro, Sidney J.L

    2003-03-15

    This work describes optimized conditions for preparation of a cobalt complex entrapped in alumina amorphous materials in the form of powder. The hybrid materials, CoNHG, were obtained by a nonhydrolytic sol-gel route through condensation of aluminum chloride with diisopropylether in the presence of cobalt chloride. The materials were calcined at various temperatures. The presence of cobalt entrapped in the alumina matrix is confirmed by ultraviolet visible spectroscopy. The materials have been characterized by X-ray diffraction (XRD), surface area analysis, thermogravimetric analysis (TGA), differential thermal analyses (DTA) and transmission electron microscopy (TEM). The prepared alumina matrix materials are amorphous, even after heat treatment up to 750 deg. C. The XRD, TGA/DTA and TEM data support the increase of sample crystallization with increasing temperature. The specific surface area, pore size and pore diameter changed as a function of the heat treatment temperature employed. Different heat treatment temperatures result in materials with different compositions and structures, and influence their catalytic activity. The entrapped cobalt materials calcined at 750 deg. C efficiently catalyzed the epoxidation of (Z)-cyclooctene using iodozylbenzene as the oxygen donor.

  11. Water splitting: Taking cobalt in isolation

    NASA Astrophysics Data System (ADS)

    Wang, Aiqin; Zhang, Tao

    2016-01-01

    The sustainable production of hydrogen is key to the delivery of clean energy in a hydrogen economy; however, lower-cost alternatives to platinum electrocatalysts are needed. Now, isolated, earth-abundant cobalt atoms dispersed over nitrogen-doped graphene are shown to efficiently electrolyse water to generate hydrogen.

  12. Evidence of Formation of Superdense Nonmagnetic Cobalt

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Singh, Surendra; Satpati, B.; Roy, A.; Basu, S.; Chakraborty, P.; Movva, Hema C. P.; Lauter, V.; Dev, B. N.

    2017-02-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure.

  13. Oxygenation of Cobalt Porphyrinates: Coordination or Oxidation?

    PubMed Central

    Li, Jianfeng; Noll, Bruce C.; Oliver, Allen G.; Ferraudi, Guillermo; Lappin, A. Graham; Scheidt, W. Robert

    2010-01-01

    The X-ray characterization of the five-coordinate picket-fence porphyrin complex, [Co(TpivPP)(2-MeHim)], is reported. The complex has the displacement of cobalt from the porphyrin plane = 0.15 Å, and Co–NIm = 2.145 (3) and (Co–Np)av = 1.979(3) Å. This five-coordinate complex, in the presence of dioxygen and excess 2-methylimidazole, undergoes an unanticipated, photoinitiated atropisomerization of the porphyrin ligand, oxidation of cobalt(II) and the formation of the neutral cobalt(III) complex [Co(α,α,β,β-TpivPP)(2-MeHim)(2-MeIm−]. Two distinct examples of this complex have been structurally characterized, both have structural parameters consistent with cobalt(III). The two new Co(III) porphyrin complexes have axial Co–NIm distances ranging from 1.952 to 1.972 Å, but which allow for the distinction between imidazole and imidazolate. An interesting intermolecular hydrogen bonding network is observed that leads to infinite helical chains. UV-vis spectroscopic study suggests that [Co(TpivPP)(2-MeHIm)(O2)] is an intermediate state for the oxidation reaction and the atropisomerization process is photocatalyzed. A reaction route is proposed based on the spectroscopic studies. PMID:20104874

  14. Comprehensive therapy in osteoporosis using a single drug: from ADFR to strontium ranelate.

    PubMed

    Manette, C; Collette, J; Sarlet, N; Tancredi, A; Zegels, B; Reginster, J-Y

    2006-01-01

    In vitro, strontium ranelate increases collagen and non-collagenic proteins synthesis by mature osteoblast enriched cells. The effects of strontium ranelate on bone formation were confirmed as the drug enhanced preosteoblastic cell replication. In the isolated rat osteoclast, a preincubation of bone slices with strontium ranelate induced a dose-dependent inhibition of the bone resorbing activity of treated rat osteoclast. Strontium ranelate dose-dependently inhibited preosteoclast differentiation. In a phase II dose ranging trial Strontium ranelate (500 mg, 1000 mg, 2000 mg/day) or placebo were given to 353 postmenopausal women with prevalent vertebral osteoporosis. At the conclusion of this 2-year study, the annual increase in lumbar BMD of the group receiving 2000 mg of strontium ranelate was + 7.3%, a significant increase in bone alkaline phosphatase, over a 6-month period and a significant decrease in N-telopeptide crosslinks throughout the 2-year period were seen. During the second year of treatment, the dose of 2000 mg was associated with a 44% reduction in the number of patients experiencing a new vertebral deformity. The primary analysis of the SOTI study, evaluating the effect of strontium ranelate 2000 mg on vertebral fracture rates, revealed a 41% reduction in the relative risk of patient experiencing a first new vertebral fracture with strontium ranelate throughout the 3-year study. The TROPOS study showed a significant reduction in the risk of experiencing a first non-vertebral fracture by 16% in the group treated with strontium ranelate throughout the 3-year study. A reduction in the risk of experiencing a hip fracture by 36% was also demonstrated in the patients at high risk of hip fracture (age > or =74 years and Femoral Neck T score < or = -2.4 according to NHANES normative value). All these results suggest that strontium ranelate is a new, effective and safe treatment of vertebral and non-vertebral osteoporosis, with a unique mode of action.

  15. Strontium iodide gamma ray spectrometers for planetary science (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Prettyman, Thomas H.; Rowe, Emmanuel; Butler, Jarrhett; Groza, Michael; Burger, Arnold; Yamashita, Naoyuki; Lambert, James L.; Stassun, Keivan G.; Beck, Patrick R.; Cherepy, Nerine J.; Payne, Stephen A.; Castillo-Rogez, Julie C.; Feldman, Sabrina M.; Raymond, Carol A.

    2016-09-01

    Gamma rays produced passively by cosmic ray interactions and by the decay of radioelements convey information about the elemental makeup of planetary surfaces and atmospheres. Orbital missions mapped the composition of the Moon, Mars, Mercury, Vesta, and now Ceres. Active neutron interrogation will enable and/or enhance in situ measurements (rovers, landers, and sondes). Elemental measurements support planetary science objectives as well as resource utilization and planetary defense initiatives. Strontium iodide, an ultra-bright scintillator with low nonproportionality, offers significantly better energy resolution than most previously flown scintillators, enabling improved accuracy for identification and quantification of key elements. Lanthanum bromide achieves similar resolution; however, radiolanthanum emissions obscure planetary gamma rays from radioelements K, Th, and U. The response of silicon-based optical sensors optimally overlaps the emission spectrum of strontium iodide, enabling the development of compact, low-power sensors required for space applications, including burgeoning microsatellite programs. While crystals of the size needed for planetary measurements (>100 cm3) are on the way, pulse-shape corrections to account for variations in absorption/re-emission of light are needed to achieve maximum resolution. Additional challenges for implementation of large-volume detectors include optimization of light collection using silicon-based sensors and assessment of radiation damage effects and energetic-particle induced backgrounds. Using laboratory experiments, archived planetary data, and modeling, we evaluate the performance of strontium iodide for future missions to small bodies (asteroids and comets) and surfaces of the Moon and Venus. We report progress on instrument design and preliminary assessment of radiation damage effects in comparison to technology with flight heritage.

  16. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells

    SciTech Connect

    Smith, Leah J.; Holmes, Amie L.; Kandpal, Sanjeev Kumar; Mason, Michael D.; Zheng, Tongzhang; Wise, John Pierce

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity. - Highlights: • Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells. • Soluble cobalt induces more cytotoxicity compared to particulate cobalt. • Soluble and particulate cobalt induce similar levels of genotoxicity. • Particle-cell contact is required for particulate cobalt-induced toxicity.

  17. Aging effects on cobalt availability in soils.

    PubMed

    Wendling, Laura A; Kirby, Jason K; McLaughlin, Michael J

    2009-08-01

    Aging processes in soils can significantly affect the potential biological availability of introduced metals via incorporation into crystal lattices, diffusion into micropores, or formation of metal precipitates on the surfaces of soil minerals. Over time, metals in contact with the soil solid phase are less freely exchangeable with the soil solution and, hence, less available to soil biota. In the present study, the effects of aging on the fate and behavior of added divalent cobalt (Co2+) in a range of soils with varying physicochemical characteristics was assessed using isotope-exchange techniques, chemical extraction, and plant growth. Following addition to soil, the Co2+ salt rapidly partitioned to the soil solid phase. Particularly in soils with neutral to alkaline pH, a large percentage of the surface-bound Co was fixed in forms no longer in equilibrium with soil solution cobalt through aging reactions. Using techniques commonly applied to estimate metal bioavailability in soil, the lability (E values), plant availability (L values), and extractability of added Co2+ salts with the mild chemical extractants calcium chloride (CaCl2) and ammonium nitrate (NH4NO3) were observed to markedly decrease with time, particularly in soils with high pH or those containing appreciable quantities of iron/ manganese oxyhydroxide minerals. Results indicated rapid partitioning of added Co2+ into isotopically nonexchangeable pools, with more than 60% of the aging occurring within 15 d in most soils. Soil pH was the primary factor controlling the rate of cobalt aging and extent of exchangeability in the soils examined. Understanding the influence of long-term aging on cobalt availability in soils is necessary to accurately assess the potential risk associated with cobalt contamination of soil environments.

  18. Synthesis and thermal properties of strontium and calcium peroxides

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H.; Kraft, Patricia A.

    1989-01-01

    A practical synthesis and a discussion of some chemical properties of pure strontium peroxide and calcium peroxide are presented. The general synthesis of these peroxides involves precipitation of their octahydrates by addition of H2O2 to aqueous ammoniacal Sr(NO3)2 or CaCl2. The octahydrates are converted to the anhydrous peroxides by various dehydration techniques. A new x-ray diffraction powder pattern for CaO2 x 8H2O is given from which lattice parameters a=6.212830 and c=11.0090 were calculated on the basis of the tetragonal crystal system.

  19. Strain engineered barium strontium titanate for tunable thin film resonators

    SciTech Connect

    Khassaf, H.; Khakpash, N.; Sun, F.; Sbrockey, N. M.; Tompa, G. S.; Kalkur, T. S.; Alpay, S. P.

    2014-05-19

    Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.

  20. The electrorheological behavior of complex strontium titanate suspensions

    NASA Astrophysics Data System (ADS)

    Zhang, Yuling; Ma, Yong; Lan, Yucheng; Lu, Kunquan; Liu, Wei

    1998-09-01

    A type of water-free electrorheological (ER) material-complex strontium titanate (STO) was synthesized by means of modified sol-gel. The ER behavior of the suspensions of STO particles in silicone oil with a 37% volume fraction was investigated systematically under both dc and ac electric fields. It is found that this ER fluid has many advantages, such as long-term stability against sedimentation, strong ER effect at low electric field, and a wide operating temperature range. The frequency dependence of ER behavior was also studied and can be partly explained on the basis of dielectric measurement.